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