This review is from: Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem (Personal Computers)
12/14/2011 Just received the Motorola SB6121 SURFboard DOCSIS 3.0 Cable Modem today. Followed the self-install instructions included with the modem, using Comcast internet, and a Medialink Wireless N router, and was up and running in 20 minutes.
Here's how my setup went. Disconnect your old modem. Connect the SB6121 modem to your internet coaxle cable. Now connect the ethernet cable to both the SB6121 modem and your computer. Power up the SB6121 modem and wait for all lights to stop flashing (must have solid lights), then power up your computer. Now, open Internet Explorer browser and wait for the Xfinity screen to automatically show up on your Internet Explorer's screen. Enter your Comcast account number and the phone number associated with your Comcast account on the screen, where asked, and press next. The SB6121 modem will then be automatically identified and recognized. Press next to accept the Motorola SB6121 cable modem, then wait a few minutes for the next screen to show up while the information is being processed, then press finished. 3 screens total. Disconnect the ethernet cable from your computer and connect it to your router. Now, power both the SB6121 and your router off and wait 10 seconds. Now, power the SB6121 modem on and wait for all the lights to show themselves. Now, power on your router. You should be able to go online wirelessly. Literally that simple. The Comcast Xfinity self-install screens did not ask me for a MAC address or a serial number. Total time - about 20 minutes to remove the old modem and install the SB6121. Best part, no having to call tech support and no frustration!