Two Comcast Modems or More at the Same Location?

How To Install Two Comcast Modems
Comcast Cable Modem
Can I install more than one Comcast modem at one location?

The simple answer is yes, but it is going to cost you for a second connection.

The following was a submitted question to me.

Message: My wife and I have two rooms with our respective offices. Our house is new and installed with cable TV/Internet cable connections in the walls of each room. My wife’s computer is connected to Comcast through a cable modem with a router. Right now I have set up a wireless connection to her computer through a wireless router in her office but the speed is diminished on my computer. The only other way to connect to Comcast through her modem would be to run an ethernet cable through the attic from her router to my office which could be dangerous.

It seems that every Comcast modem has its own unique MAC address. I do have a another Comcast modem the same as my wife’s modem which I purchased on EBAY. Is it possible to clone the MAC address on my wife’s Comcast Modem into a router in my office and connect the purchased Comcast modem into the cable connection in my office and be able to get on the internet? Thanks



Answer: Hello H,

What I think you’re asking is,

Can I hook up another Comcast modem using the front end of a router, with the cloned address of the other Comcast modem?

First off, you are right, every Comcast modem does have its own unique MAC address.

The router is meant to be on the output of the Comcast modem, not the input of the Comcast modem. Routers make the Comcast modem think that there is just one unique IP address on the output of the modem. But, in actuality, the router routs the information to each computer on the Local Area Network (LAN). The input from Comcast Central goes into the modem from the coax cable, and not the other ethernet cable for the LAN network.

I too have an extra Comcast modem. When I upgraded to digital voice with Comcast, they installed another modem with phone built-in. My original modem was purchased by me at a local store. When the service guys did the install, they had to call in the new modem to Comcast Central.

My understanding is that only one modem of that address can be installed at a time. If you think about it, this makes sense, otherwise the system would not know which modem is handling the information. However, if you want to pay for another Comcast account, I think you can get two Comcast modems hooked up at the same time but with unique MAC addresses. Gamers, who like lots of speed have done this. Comcast then splits the coax cable and runs it into both modems. Then you have two outputs (one from each modem). Note: just as your router assigns a unique IP address to each computer, the Comcast DHCP system assigns an IP address to each modem.

As far as speed is concerned with your current wireless setup, what is your cable Internet speed with the current setup?

Compare your speed at both computers.

How far is your wireless computer from the office router?

Certainly the best connection is to have a cable going to both computers from the router. Many times the problem with wireless is the location of the router or the location of the antennas on both the computer and the wireless router, and that they are behind shielded walls or just long distances.

So, as it is, I think you have a spare second modem that can only be used if you pay for another hook up.

Read other posting with a conversation with Comcast for additional modem, router, switch, and hub information for a Comcast home networking system.

Jim Warholic

Marketing Solutions

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.

Internet Speed Test For DSL, Cable Modems, And Dial-Up

Verify Your Upload And Download Speeds From Your Internet Service Provider

Check Your ISP Internet Speed Connection. Are you curious to know how fast a connection you have through your Cable, DSL, or Dial Up connection? Well, there are numerous free services online that you simply go to their websites and select a location to connect to online and the program tells you how fast a connection you have to and from that web location.

Here are a couple of providers of this service.

Speakeasy.Net SPEED TEST

What these tests are good for is determining the actual speed that you can really upload, download, and surf online when using your Cable, DSL, or Dial-up modem. Many of the ISP service providers claim that you can go at a certain speed, but now you know how to verify if what they say about your Internet connection is true. One note and suggestion: Try a couple of different website locations to make sure that the speed is not being slowed down by a slow website connection on the opposite end as opposed to the ISP’s Internet pipe throughput.

If your Cable or DSL Internet connection is not up to speed, you might try getting another IP address for yourself too.

Signed Jim

Professional Internet marketing services to help get your business found online.