Just been pulling my hair out for 1.5 hours over a new wireless router install which supposed to be a no brainer to install, which turned out to be true BUT a BEEMASTER QUICK TIP (patent pending - lol) PULL the power cord to the modem for at LEAST 30 full seconds then replug it in THEN plug in the router: if I had known this QUICK TIP 2 hours ago, I'd have saved a lot of hair pulling.
I knew I was close I had in the NETWORKING SECTION both the router and modem showing enabled, so I figured it was down to an IP issue or something simple. I knew choosing DHCP was the RIGHT choice for Comcast (at least here) and nowhere in the install instructions of the router did it say to PHYSICALLY pull the power cable (JUST) to turn it off at the switch - ugh.
So, if Santa brings wireless networking to your home this Christmas, pull the power cord out of your cable modem, let it UNATTACH itself from the computer it is dedicated to, and then plug it in again. Hopefully, that is ALL you will need to do to get your system up and running!!!