I've been using a Netgear Zoom 5341J cable modem with Comcast since I turned cable internet on over 2 years ago. It works just fine. I got mine at Amazon.......This isn't a cable modem btw
It's a telephone type modem, not sure why I need it for, since I don't have phone service anymore, I was told that I can't just buy outright online since it won't work that way, even same model, Only way is to buy is at a Comcast kiosk either BB or other stores with a schedule install, Heard the price was really high that way.
Amazon product ASIN B0063K4NN6