Bought the SB8200 3 months ago, but didn’t actually provision it with Xfinity until 2 weeks ago.  I only have 13 devices needing Internet access through my router.  A few days ago, all my devices would drop their Internet connection for a min or two, then it would restore connectivity.  However, after this last instance of dropped connectivity, service never restored.  Xfinity can see the modem and can restart the modem remotely, but router never sees the connection to the modem.  After trying with a spare router and getting the same results, nothing left to conclude except the SB8200 is not passing the IP address from Xfinity to the router OR the WAN port on the SB8200 has completely failed.  I bought a new router (not a Arris modem!), provisioned the new modem with Xfinity, and voilà, the router is now working perfectly with my new modem and all my devices are reconnected to the Internet.  Looks like I wasted my $s in purchasing the SB8200.