Forcing Comcast ISP to New IP Address With Router and PC

Slow Speed Broadband Connections With Comcast Are Not The Norm

If you are experiencing slow speed broadband internet problems, or you are a WoW gamer, and your World of Warcraft connection has excessive lag, then you may have the following IP problem with Comcast ISP or your Cable or DSL Internet Service Provider.

There does seem to be a situation that occurs from time to time with Comcast high speed Internet service that is very peculiar. It seems as though some of the IP addresses provided by the automatic DHCP configuration at Comcast produce a very slow Internet connection. Getting a new dynamically generated IP address from the Comcast system can help improve your connection upload and download speeds issue. Learn how you can do this easily with a wired or wireless router and your computer.

So, what do I have to do to change the IP address assigned to me by my Internet service provider?

Change Your IP Address: Quick Summary Answer

To get a new IP address, start by cloning another computer’s Mac address using a router hooked up to the cable modem. Then reboot the cable modem, and if everything went OK, the ISP provider’s DHCP system will assign another IP address for your Internet service automatically. Read the IP address change details below.

Test your Internet speed using any one of the modem speed tests online. Then check your IP address using the check my IP address websites. Write both of these down to use later for comparison purposes. Note: The source website server is also a factor for upload and download speeds to your computer. So, it’s also a good idea to note this source website server from the modem speed test, for checking your online upload/download speeds in later comparisons.

Understanding the technical terms
IP address Types (Dynamic and Static)

There are two types of IP address that can be assigned. Dynamic and Static. When a computer is configured to use the same IP address each time it powers up, this is known as a Static IP address. In contrast, in situations when the computer’s IP address is assigned automatically, it is known as a Dynamic IP address.

Sticky Dynamic IP Addresses

A sticky dynamic IP address or sticky IP is a term created by cable and DSL users to describe a dynamically assigned IP address that does not change often. This is however an informal term, as a sticky IP does not differ in any way from other dynamic IP address. Most cable and DSL ISPs assign dynamic IP addresses. However, if you have Comcast Business Internet Service Class with a static IP address or have requested and pay for a static IP address with your home Internet service provider, the only way to change this is for Comcast, other cable companies, or DSL service providers to do it on their end.

Even though IP addresses may not change often for cable or DSL users, the addresses are still controlled by the standard DHCP process. Since the modems are often online for extended periods of time, the leases on the IP addresses are commonly renewed, and therefore may not change.

Dynamic Host Configuration Protocol (DHCP)

The Dynamic Host Configuration Protocol (DHCP) automates the assignment of IP addresses, subnet masks, default gateway, and other IP parameters. There are four modes of operation: dynamic allocation, automatic allocation, static allocation, and manual allocation.

  • Dynamic allocation: A network administrator assigns a range of IP addresses to DHCP, and each client computer on the LAN has its IP software configured to request an IP address from the DHCP server during network initialization. The request-and-grant process uses a lease concept with a controllable time periods, allowing the DHCP server to reclaim (and then reallocate) IP addresses that are not renewed (dynamic re-use of IP addresses).
  • Automatic allocation: The DHCP server permanently assigns a free IP address to a requesting client from the range defined by the administrator. This is like dynamic allocation, but the DHCP server keeps a table of past IP address assignments, so that it can preferentially assign to a client the same IP address that the client previously had.
  • Static allocation: The DHCP server allocates an IP address based on a table with MAC address/IP address pairs, which are manually filled in (perhaps by a network administrator). Only requesting clients with a MAC address listed in this table will be allocated an IP address. This feature (which is not supported by all routers) is variously called “Static DHCP Assignment” (by DD-WRT), “fixed-address” (by the dhcpd documentation), “DHCP reservation” or “Static DHCP” (by Cisco/Linksys), and “IP reservation” or “MAC/IP binding” (by various other router manufacturers).
  • Manual allocation: The DHCP server does not assign the IP address; instead, the client is configured with a user-specified static IP address.

Many DHCP servers can manage hosts by more than one of the above methods. For example, the known hosts on the network can be assigned an IP address based on their MAC address (static allocation) whereas “guest” computers (such as laptops via WiFi) are allocated a temporary IP address out of a pool compatible with the network to which they’re attached (dynamic allocation).

How do I get a New Comcast Dynamic IP Address?

The following Comcast IP address change process is for dynamic addresses. If you have a router installed after your Comcast modem, then this next procedure is very easy to get the Comcast system to dynamically generate a new IP address. If you do not have a router, I strongly suggest you get one to have an extra firewall between your computer and the Internet. Most IP addresses given out by the Comcast DHCP system are in a leased mode. This means that if your modem is turned off for several days or more, the IP address goes back to a group of IP addresses to be automatically reassigned to other users. Turning off the modem for short periods of time will not reset the leased IP address because the modem is assigned the IP address based on the original computer’s MAC address. Every type of networking hardware has a unique code that is the Media Access Control address or MAC address for short.
Linksys Router Clone Mac Address

Linksys Router Clone Mac Address

Router’s also have a MAC address. Once this MAC address is synced up with the cable modem, the Comcast DHCP system assigns the IP address to the online outlet. However, if the MAC address is changed, the Comcast DHCP system assigns a new IP address to the online outlet, because it thinks it is a different location. Each computer, with a network card, also has unique MAC addresses. If a person were to hook up a different computer directly to the cable modem, it is likely that a new IP address would be assigned by powering down and then up again the cable modem. However, with a router it is much easier to assign a new MAC address to the router itself. Most routers today have what is referred to as clone the MAC address. This feature allows the user to make the router look like any one of the computers that reside on the premises. Simply logging into the router through a web browser by typing for Linksys or Cisco, or do a search for Router IP Address to find your particular brand.

linksys-router-setup Routers Login IP Addresses – Use The Following Format 192.168.x.x

Click on those links above to try logging into your router. Those specific router links will open in a new window or tab, or right click from your browser to open in a new window or tab so you can follow the instructions at the same time you log-in to your router. Here is a PDF document link to brand and model specific default router information list of Manufacturers, Models, User Names, Passwords, and Default IP addresses. Note, before attempting this procedure on your router, I suggest you print this information out for reference. Use the print button from the permanent link to this how to get a new IP address article. Also note that a router’s IP address can also be changed too. If you can’t get a log-in screen on your browser, then you aren’t getting to the router’s proper IP address for your local area network. Also try logging in to your router with a different browser like Firefox, Google Chrome, Safari, Internet Explorer, Opera, Camino, SeaMonkey, Flock, and others. If that doesn’t work, then do a Google Search for your particular router brand and model number IP address. If after finding the correct IP address for your router, but still can not get a login screen prompt, you might have to do a hard reset of the router’s firmware settings (usually a recessed button). However, if and when you do this, the router will revert to the defaults, and you will loose all your custom user name, password, wireless settings such as SSID and encryption codes, along with other TCP and UDP port settings that might be assigned for online game hosting like WOW – World of Warcraft private servers, if those online gaming TCP and UDP port settings were customized by you or someone else to begin with. After doing a hard router reset, you would then have to re-enter all the information again.

After you get to your router’s IP address and you have a user name and password prompt, then type in the login name and password. Hopefully you have changed the user name and password for security purposes (and wrote them down) when you first set up the router and changed them from the default settings. The browser is your window into the router’s operating system and allows you to login and set up the router using the internal configuration program. Find the area of the configuration program (usually a tab or hyper-link) where you can clone your MAC address and perform a clone to a new MAC address. Before you clone the MAC address, write the current MAC address down. This is so you can put it back to the original if you need to. Once the cloning of the MAC address is done, then you can try a release IP address and renew IP address in the router’s programming structure. This sends a release the lease to the Comcast DHCP and then renews with a new IP address. Suggest powering down the cable modem, router, and computer at this time. Then re-power everything back up and you should have a new IP address.

Now go back and check to see what your current IP address is and the speed at which you can upload and download from the Internet using the online modem speed test. Hopefully you are now running at light speed and no more WoW lag for the active gamer.

Good luck.

Contact Jim for your online business solutions. Professional Internet marketing services for your B2B or B2C business today. Get your website found online and start getting more customers now.

PS This particular problem I have personally seen, and have been able to rectify Internet connection speed issues using this technique. This may not be your particular problem, but it’s worth a try. This new IP address solution might also work for other high speed broadband ISP providers. Give it a try with your Internet Service Provider and let our readers know if it works for your DSL or Cable ISP company.


I have been trying to get a new IP at Comcast more for
security reasons. Once your surfing habits are known if you hit a site with mal-intent then you are vulnerable, or some hackers get it and then can always find you. The 16 hour unplug did not work. I will try your suggestion. I finally got an iMac and while I have gotten no viruses I am sure I have been hacked several times.

I really like Ubuntu too. It’s gui reminds me of a big, homemade, ice-cream cone. I started trying Linux back when Caldera first came out with it. Then Lindows. Ubuntu is really the first I really like and don’t have to understand all the syntax that makes dos look like a first grade reader. Gads. How do these people remember all those things: xy- min -x
be sure to apply all the needed primary lines before using this in terminal. ;>(
And be sure to make backups before doing this? :>(
Just in case you need to install a backup in preboot mode. :>(

It just works.

I have just tried the Vista overlay on my XP install.
Major Geeks might have had it but if you don’t have XP it won’t do you any good.
W2K is probably better than XP but when I went to the W2K MS opening at FSU or USf Tampa,2000, to get my free W2K they were out. I emailed them but I think due to some of my complaining emails they refused to send me my free copy. Shouldn’t have flamed them with my displeasure over their practices. Updates? Etc.

Thanks for article. Will try to get new IP and then use to try to keep it safe and private.



This did not work for me at all. I am very familiar with all of these settinsg and options. Uisng a DI-707P router (DLink) I went into Home – WAN and clicked Clone MAC Address. Then went to Status – Device Info clicked DHCP Release followed by DHCP Renew. The router never did re-establish connection with Comcast. On that Device Info screen I did notince that the LAN MAC Address remained at the old value while the WAN MAC Address had changed to the cloned one. Any hints?

Jim Warholic

A couple of questions and observations in your description of what you did.

First off, did you do a complete reboot of the Comcast modem? You might have to completely reset the Comcast modem with the reset button from the back side. Normally this reset button is recessed and requires a small paper clip to push it in. Simply unplugging the Comcast modem is not good enough because the new ones have battery backups built in to them.

FYI, I have still used this option to get an IP address a number of times since I originally wrote this article. The process has worked for me.

Try restarting both the DLink router and the Comcast modem at the same time. Just remember you would want to do a hard reboot reset on the Comcast modem.

My Comcast modem is the Motorola SBV5220 Cable Modem. It has digital telephone, cable TV, and high speed Internet built into one unit. I am using a Linksys SRX200 Wireless G Broadband Router.

Give it a try, let us know what happens.

Good luck.


ok so if i wanted to do this more then 1 time (because it worked beautifully the first time!) would i have to fully reset my router or what would i have to do? i tried to do it again just for kicks and it wouldnt allow me to connect to the internet if i even so much as changed 1 number or letter on the cloning of the mac address option. when i hit the “clone” button on the setup it only gives me 1 sequence of numbers and letters and thats it. so i guess im just wondering how i would go about doing it again if i ever needed another new ip?

PS. once i disable the mac address cloning option in the setup the internet stops working. any help with this problem would be greatly appreciated also as im definitely new to this.

thx in advance -Explodey

Jim Warholic

A couple of points here.

First off, I don’t think you can just change the MAC address by one alpha number or digit and expect it to work. I suspect it has to do with MAC addresses in general and how they are verified by the system. I’ve tried to do that in the past myself, and it doesn’t work. It’s as though the MAC address has to be a good MAC address, and the system somehow knows that the MAC address number being changed by a number or two is not valid. I think it is because the MAC address is both hardware and software verified. For example, a NIC card (Network Interface Card) has the MAC address hard coded into the hardware.

With the router MAC address cloning option provided by most router manufacturers, the routers have a built in software cloning program that makes a valid MAC address using a verified MAC address to begin with from your local computer NIC card.

However with changing the MAC address the first time, and wanting to change it again in the future, I went to another computer that I had on my local network, (that was previously assigned the MAC address to the router) and reapplied the IP process change, by cloning the MAC address of this old computer (with the old NIC card), and the Comcast DHCP system gave me a new IP address, even though that was once a MAC address used in the past with the Comcast DHCP networking protocol.

I suspect the DHCP system provides another IP address because of the extended amount of lease time between using that MAC address in the past and the new one in the present.

I would suggest not changing this MAC address too often. Don’t ask how much too often is…

Now, if you disable the MAC address clone on the router, you might not have a valid MAC address to begin with.

I’ve done a little bit of research and found some interesting downloads at CNET for various aspects of MAC addresses and helpful networking utility programs. The page is MAC Address news, reviews, and downloads on CNET.

I have not tried any of those MAC address programs myself, so you are on your own with those.

Good luck, and do the right thing.


This worked so damn well that I want to nominate you for President (at least one candidate would have done something that works). I have been trying to reset my IP address for months… you are the man!


Well well well, i cannot believe there is a real solution. I havent tried it yet but i believe it works. It sounds legit. only problem is when do u reset the router modem and computer? after the release/renew or during or before?


The release/renew is not really required. What is required is resetting the router and the modem. Once the router has been given the new MAC address, then reset the Comcast modem. I don’t believe the release/renew from the router will trigger a new IP address to be assigned to the modem. However, you can try the release/renew after you set the MAC address on the router. If that doesn’t work, then reset the modem using the small recessed reset button on the Comcast modem.


thanks for this. Is it safe to keep the router settings for the mac address as cloned or should you disable it once you get a new IP?

Jim Warholic

That’s an interesting question. Never thought about. I don’t believe it matters once the MAC address has been cloned to keep the setting in the enable or disable mode. I think the enable and disable mode is a form of double checking safety feature on cloning the MAC address in the first place. I think you can disable it after you clone the MAC address of the computer you are using to log in to the router, and it should stay loaded, but I have not tried it myself.


Be careful, This technique may put you in violation of comcast’s terms of service. This can very well fall under tampering with service. I would recommend against this because what jim is not telling you is that even though you have changed your ip, your cable modem is on a different provisioning system that is assigned an,(within comcast own network) ip address that never changes. All the ip addresses that you think your changing, are being logged to one ip address, you account, your cable modem where they bill you. I have heard though that if you change it too much they send the modem back to “walled garden” to try and force you to call them.


Jim Warholic

I agree that Comcast is most certainly logging the IP addresses assigned to your unique cable modem MAC address. However, I am not sure that this is in anyway a violation of Comcast’s terms of service policy. Think about this for a moment. Let’s say I am not using a router for a local area network, and only have one computer hooked up to the Comcast modem directly. Then, I remove that one computer and hook up a different computer to the cable modem. Both computers have different MAC addresses, and when I remove one and place the other one on the Comcast modem, the Comcast Internet system will generate a new IP address from Comcast to your account. This is because the Comcast system will see a new Network Interface Card, with a completely different MAC address. The MAC address is what triggers the new IP address from Comcast DHCP. Removing one computer from a residential service premises and installing another computer at that same residential service premises, happens all the time throughout the Comcast network. Heck, even replacing the router with a new router will cause the Comcast system to generate a new IP address. This is because the new network router (if the MAC address has not cloned from your computer) has a new MAC address fresh from the factory. People upgrade and purchase new routers all the time.

But, with all that being said, I did say earlier that you should not do this too often. I also said, don’t ask me how much too often is. So, I acknowledge what the anonymous person has said above as a possibility, and be warned, you take this risk on your own accord. I strongly recommend you do a Google Search for “Comcast Terms of Service” to read and verify for yourself the Comcast terms of service and what the acceptable use policy is, before proceeding.

While this comment has been directed toward the Comcast system; I recommend that you review your cable provider or DSL provider ISP’s terms of service acceptable use policy before proceeding with a forced IP address change.


I can say that the “walled garden” does exist. you are able to change IP’s 5-6 times before you are locked out and forced to go back to your original MAC if you want service. This seems to last for X hours – I haven’t determined how long yet – somewhere between 6-24. then the process starts all over again.

It doesn’t matter if you physically change the MAC on your NIC and routher or just the router. The same result will occur.

I know people get around this all the time, but I have no idea how.

Jim Warholic

Hi Anonymous,

It sounds like you are changing your IP address too often. That was the IP point I was also making in my comment. I was giving the example of people actually replacing hardware, as in the case of a computer, NIC card, or router, and comparing that to changing the MAC address via cloning using the router as mentioned in the article.

I will say this, I think Comcast is keeping past IP addresses assigned to the cable modem in a database for a longer period of time now as compared to when I first wrote this article. If an IP address you had previously assigned to you, is now assigned to someone else, or not in a shared IP address condition, or sharing of that IP address is maxed out (maximum total number of IP users sharing one IP address) in the Comcast system, then more than likely you would get a different IP address. However, if the IP address is still available and not reassigned to someone else, Comcast could give you the same IP address back when going back to an old MAC address. Comcast has many options that they could do. Who knows, Comcast folks might have read this article and implemented changes in their system.



I’ll have to try this stuff. Also helps that I downloaded a MAC changing program from CNET though I don’t know if this program will do its job yet.

Thanks for the info. πŸ™‚


I have a comcast modem a terayon and it does not have a reset button on it anywhere. So how would you reset it?

Jim Warholic

For the Terayon cable modem, try to reset the modem by unplugging the power cord from the modem and wait 1 to 2 minutes. Then plug it back in.

It looks like some of the Terayon modems do not have a hidden reset button, and the only way to do it would be a power down and a power up again.


Thanks worked for me appreciated you help very much. πŸ™‚ I didn’t know anything about this but you cleared it all up for me with your tutorial.


I have the opposite problem.
I want to keep an IP address but keeps changing every couple of days or so…… any suggestions on how to keep an IP (comcast) for longer time??


To the guy wanting to keep the IP… go to and register a dymanic name. That's what I've done. depending ont he router you have there is a spot for DDNS too so you never have to go in and reconfigure. Now… if you need to have that exact IP… I suggest a call to comcast and a change in your plan, ask for a static. But DynDNS is free… and it works!

I came here looking to change my IP cuz I keep renewing the same one for the last 8 months (go figure). I just wanted to make sure my DDNS was working… it is.

Thanks for this post! Worked great! (even changed it 3 times to test.)


I have an SBV5220 and am trying to setup a wireless router. I have been at this for about two years,not continuous of course, but have tried two different Belkin routers-f5d8236-4 being the latest. I have had tried four different computers as well. The problem is that the router is losing connection intermiitently to the internet or the modem. When the wireless is up, the connection is often very slow, but not always. Belkin says its not their router and Comcast insists its not their modem, but they would install me a wireless router for $149. The Comcast modem is the only common denominator (all cables have been replaced). I have been through the MAC address cloning process and several power down/up cycles. Before I take this router back, do you have any suggestions?

Jim Warholic

I would want to know how the router's wired portion speed test checks out. If you do an Internet speed test while hooked up to the wired portion of the router and compare that to the wireless router test, it would be very helpful to determine what is going on. I still suspect something is going on with the wireless routers or there may be some wireless interference going on close by the router, or even within the same transmission footprint location.

The various frequencies for wireless routers are as follows for 2.4 GHz (802.11b/g/n):

There are 14 channels designated in the 2.4 GHz range spaced 5 MHz apart (with the exception of a 12 MHz spacing before Channel 14). As the protocol requires 25 MHz of channel separation, adjacent channels overlap and will interfere with each other. It ranges from: 2412 MHz to 2484 MHz

The various frequencies for wireless routers are as follows for 3.6 GHz (802.11y): range from 3657.5 MHz to 3690.0 MHz.

On wireless routers in the 5 GHz (802.11a/h/j/n): the frequency range is from 4915 MHz through 5825 MHz.

Typically the lower the frequency, the further the transmission distance given the same power outputs.

Some frequencies have more interference than others. Also, you can select different frequencies for transmission within the router. Sometimes one frequency is being affected by another user's router in the neighborhood. Try selecting a different frequency and see if that gives a different result.



Hello all. I am very new to all of this "MAC and NIC" stuff.. and I thought I had it pretty much conquered. I attached my linksys router (wrt54gv5) to my cable modem and to my computer. my son wanted to connect wirelessly to his playstation 3 game, and it worked fine. about an hour later, my comcast modem (arris touchstone) (model-TM402P/110) was stating that it had little or no connectivity. then it said that the ISP hadnt given me a new IP address. but my linksys router was connecting just fine. Then I wasnt able to connect to the internet, but my son was still able to play his playstation 3 online wirelessly. can anyone please tell me what I am doing wrong to cause this conflict, and what I can do to get it resolved. I have a Dell Dimension E310 running windows xp service pack 3. Like I said, it was working fine up until an hour later. I configured my linksys using the info directly from the linksys website. here is the link to it, if this helps…

Also my cable modem is connected to my PC with a USB cable. It wasnt connected at all using an ethernet cable up until now since i'm using the linksys router. Can the USB cable remain or can that cause some problems with an ethernet cable being connected as well..

any help would be greatly appreciated!!!

Jim Warholic

The Arris user manual states you can connect to both the USB and the Ethernet port at the same time:

Arris User Manual

Page 11

"Ethernet or USB?

There are two ways to connect your computer (or other equipment) to the Telephony Modem. The following will help you decide which is best for you:


Ethernet is a standard method of connecting two or more computers into a Local Area Network (LAN). Use the Ethernet connection if your PC has built-in Ethernet hardware, does not use Windows, or you want to share the Telephony Modem connection with several computers.

Note: To connect two or more computers to the Ethernet port, you will need a hub or broadband router (available at computer retailers).

The Telephony Modem package comes with a 6-foot (1.9m) Ethernet cable (the connectors look like wide telephone connectors); you can purchase more cables if necessary at a computer retailer. If you are connecting the Telephony Modem directly to a PC, or to an Ethernet hub or broadband router with a cross-over switch, ask for Category 5 (CAT5) straight-through cable. If you are connecting the Telephony Modem to an Ethernet hub or broadband router without a crossover switch, ask for a Category 5 crossover cable.


USB (Universal Serial Bus) is meant for connecting a variety of accessories, such as keyboards, mice, printers, and communications devices (including Telephony Modems) to a single PC. Use the USB connection if you have only one computer, and the computer is using a Windows operating system (Windows 98 Second Edition or later), and has no built-in Ethernet hardware. The Telephony Modem package comes with a 5-foot (1.6m) USB cable.

Both Ethernet and USB

If you have two or more computers, you can connect one computer to the Telephony Modem's USB port and one or more other computers to the Ethernet port. To connect two or more computers to the Ethernet port, you will need a hub or broadband router (available at computer retailers).

For more information about connecting two or more computers, contact your cable service provider."

However, with that being said, I would try to connect your computer using the router to see what happens. Maybe the modem has a problem or has become unstable with both connections at the same time.

You could also try resetting the cable modem.

Page 48:

"Using the Reset Button Use the Reset button, on the back of the Telephony Modem, to reset the modem as if you power cycled the unit. You may need to reset the Telephony Modem if you are having problems connecting to the Internet. Using this button will be rare.

Use a pointed non-metallic object to press this button. The photo to the left shows the location of the Reset button.

The Reset button is recessed to prevent accidental resets."

I have seen other types of cable modems that seemed to function better on either the USB port or the Ethernet port, but had difficulty functioning on both at the same time.


A good article with much explanation. However, can this be condensed into a simple step-by-step procedure with no background information? That would be helpful to me. Thank you!

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