How to Self-Install Your Comcast Modem

Xfinity Self-Install Instructions

Save money by self-installing your Comcast Xfinity cable modem! With our step-by-step guide, you’ll be able to complete the activation process in just 30 minutes to 1 hour. Whether you’re installing a telephone modem or a cable modem router combo, we’ve got you covered. Say goodbye to monthly modem rental fees and enjoy fast and reliable Xfinity internet. Start your self-installation journey now!


Step 1: Unpack the Cable Modem

The first step in the installation process is to unpack the Comcast cable modem. Carefully remove the modem from the box and make sure that all of the necessary components are included. These components typically include the modem, a power cord, an Ethernet cable, and any accompanying documentation.

Step 2: Connect the Power Cord

Once you have all of the necessary components, you can begin connecting the modem. Start by connecting the power cord to the back of the modem. Plug the other end of the power cord into a wall outlet and turn it on.

Step 3: Connect the Ethernet Cable

The next step is to connect the Ethernet cable to the back of the modem. The Ethernet cable should be connected to the same router that you use for your internet connection. Need an extra Ethernet? Grab one from here!

Step 4: Activate the Modem

Once you have connected the power cord and the Ethernet cable to the modem, you can activate it. To activate the modem, you will need to call Comcasts customer service department. Comcast customer service will ask for your account information and then the serial number and/or CMAC on the bottom sticker of your modem. They will then take a few minutes to activate your modem for you.

You can also activate your device online using Xfinity’s self-activation portal by going to You’ll be prompted to log into your Xfinity account and then it will take you through the activation steps to get your equipment added to your service.

Step 5: Connect Additional Devices

Once you have activated the modem, it’s generally a good idea to test your conection by going to 1 or 2 sites to see if you can access the internet. After verifying your internet connection is working, you can begin to connect additional devices. This includes computers, smartphones, tablets, and gaming consoles.

If your modem is a modem-router combo device, you can connect your devices to the WiFi network broacast by your modem router. If your modem does not have a built-in wifi router, you’ll need to use an Ethernet cable to connect directly to the modem or add a separate wireless router to your modem, and then connect your devices to that.

And that’s it! Once your devices are all connected to your new modem, you have successfully activated your modem and are ready to start using the internet!


If you are having any issues with the modem or your internet connection, you can try troubleshooting the issue. The first thing you should do is to make sure the modem is properly connected to the router. If this does not resolve the issue, you can try restarting the modem. If the issue persists, you may need to call Comcasts customer service department for assistance.

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