I had the same problem. I just got off the phone with Apple. I had just replaced my old comcast modem with the new XFinity Modem. When I tried to go to the Apple TV it was acting strangely When I rebooted, I got the settings or computers thing. They had me:
1. Reset the Apple TV to original settings
2. Unplug my Time Capsule
3. Unplug my XFinity Modem
4. Wait about 2 minutes
5. Plug in the XFinity Modem (it takes FOREVER for the new XFinity modem to come up, so give it a couple of minutes)
6. Once it shows Online, plug in the Time Capsule
7. The Time Capsule shows a yellow light. Even direct connected computers still don't have an internet connection
8. After a few minutes the XFinity network connects and the direct connect computer works
9. Short time later, the Time Capsule light goes green and the wireless iMac is working
10. Go to the Apple TV and Click English and then select my WiFi network and type in the interminable password
11. Connection established and it looks normal'ish
12. Sign in in settings ->ITunes Store with my apple ID and password
An I'm on. Whew!