Thanks for posting to the Xfinity Forums. Sorry for the experience you're having. By chance, have you tried performing a system refresh on your box (Press A on your remote, then click on system refresh)? I like to take a look at your account on the back end to see what more would be causing this like possible signal issues, or if it is the actual box itself. In order to assist you, please send me a private message verifying your first and last name. To send a private message click on my name "ComcastChe", then click send a message.
I wasn't able to confirm whether or not this has been resolved. If you are still having issues, please reply to my last private message and I'd be happy to continue assisting you. We appreciate your service. Take care.