I recently upgraded all cable boxes to support 4k. This included two of the Xi6 boxes.
When I initially turn the tv and box on(power on cable remote) I am greeted with a black screen but no error code. I can access the xfinity menu and watch anything there, as soon as I exit out to licve tv, the live bradcast is back and working normally. At times, I do encounter a blue screen with the reccomendation of restarting all set top boxes or you have caught us in the middle of a household update.
The boxes are hardwired as to eliminate any wireless issues. Comcast support is telling me I need a technician but that since this was a self install, there would be a 70.00 fee.
I have verified that the gateway supports the the xi6 boxes.