When you first subscribe to high-speed Internet access from Comcast, you will receive a standard cable modem with ports for Ethernet cables. However, if you want to set up a wireless network in your home or office, you will need to purchase a separate wireless router. After that, you can configure the wireless router to connect to your modem and create a local wireless network.
Ensure that the Comcast cable modem is powered on and receiving an active network signal. Usually, the modem is receiving a signal if the "Data" light flashes.
Plug one end of a standard Ethernet cable into the output port on the back of the modem.
Connect the other end of the Ethernet cable to the "WAN" or "Wireless" port on your wireless router. The router should not be powered on yet.
Plug the wireless router into its power adapter to turn on the device.
Use a pen or another device with a sharp point to press the "Reset" button on the back of the Comcast modem. The modem will reboot and begin communicating with the wireless router. The router will receive the Internet signal from the modem and create a wireless network.