I got the SB8200 from Amazon. I got a LINKSYS MAX-STREAM AC2200 wifi router from Bestbuy.
I have the GB service.
when I connect my PC to the Modem - it works.
when I connect my wifi router to the modem - it does not get a IP or connect to the internet.
comcast support has not been able to help.
Did you reboot the modem after you disconnected your PC and before you connected the router to it?