TV box reboots by itself every 3 to 5 minutes

Xfinity X1 box plus four "satellite" boxes.  The main X1 box works just fine.  However, one of the satellite boxes will come on, then go out after 3 to 5 minutes, giving a "No signal present" message.  It will then reboot to the "Welcome" screen, and come back on after a few minutes, lasting 3 to 5 minutes before going out again.  This cycle repeats indefinitely.

I have tried unplugging and reconnecting all cables, rebooting the X1 box, and doing the recommended troubleshooting thru the Xfinity App, refresh signal, etc.  All of these things were tried multiple times. 

I then went to the local Xfinity store and exchanged the box.  It didn't solve the issue.  It seems to me that this rules out the box being the issue, it would seem to be something else. 

I am unable to speak with anyone about this issue; the on-line A.I. help is of no help, it just tells me to do the same things over and over.  I need to get this resolved.