Setup and activation for Comcast XFINITY

You will need to connect and activate your modem with your Comcast XFINITY service once you have it installed. If you need to get cable modem service, please speak with Comcast prior to installation.

Be sure you have your Comcast XFINITY account information handy. Comcast will need to know the account number of your cable service and the phone number associated with your account for activation. This can be found on your Comcast monthly bill statement.

Also, Comcast Xfinity will need to know your cable modem's MAC ADDRESS, called CM MAC. You will also be asked for your cable modem's model name, model number, and serial number. This information is all printed on a label on the bottom of your cable modem.

You will need to provide this information when you order cable modem service, or when calling Comcast after installing your modem, or by filling out the account setup web page that may appear when you first connect your cable modem to Comcast’s network.

Installation / setup advice

Review the Quick Start that came with your cable modem for detailed installation instructions. The installation instructions are also online. To access your cable modem’s documentation click and then select the product page for your model.

First turn off and unplug all existing routers and modems. Turn off the computer that will be used to activate the device.

It is recommended to use an Ethernet cable instead of a wireless connection during setup to minimize activation issues.

Follow the Quick Start instructions to connect your cables. Ensure that your coaxial cable is properly tightened.


Once all cables are attached, turn on your cable modem. It normally takes 5 to 30 minutes to establish an Internet link the first time a cable modem connects to a cable service provider. This allows the cable modem to connect to the appropriate channels for communication. You’ll see the DS, US, and Online modem lights on your cable modem flashing until the Online light stays steady green to signal success.

Once the Online light is on steady, you are ready to start the Comcast activation process. Turn on the computer that is connected to the cable modem. ( if you have a router connected to your cable modem turn it on first wait a minute then turn on your computer.)

Open up your Web browser on the computer that’s connected to your cable modem then refresh the screen or try to go to a Web site.

Comcast typically brings your browser to a registration page. In that case, follow the instructions on this registration page to register your modem. If the activation page does not appear automatically, please go to for more information and a link to activate your modem. Then follow the onscreen prompts. You will need to provide your Comcast Account Number and the phone number connected to the account.

If the page does not load, you may need to delete any default/existing DNS Server settings on the router/computers, and then try accessing Comcast's activation page again.

If you have trouble activating online and no registration page appears after following the instructions above, you may need to call Comcast at 855-652-3446 to register your modem. Comcast may ask you to provide the following information which is all located on the label on the bottom of your unit.

  • Modem Manufacturer
  • Modem Model Number
  • Modem Serial Number
  • Modem MAC Address

Once your cable modem is registered either online or through a conversation with someone at Comcast, Comcast will provision your cable modem service. Typically this takes less than 5 minutes, but in some cases this may take up to 30 minutes to complete.

To verify that your cable modem is working, open your browser and go to a familiar Web site.

For more help:  Comcast Support

Additional helpful Home Networking Support is provided by Comcast XFINITY at


For more help:  Motorola Support or call us at 1-800-753-0797

(Monday-Friday 8:30am-10:00pm, Saturday 8:30am-5:00pm ET)


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