Contour Xi6 receiver - screen goes black randomly

My parents have a Contour Xi6 receiver - their only cable box.  Every other day or so, the screen goes black for 30 seconds and then comes back to life.

I've tried another HDMI cable and it didn't help.

Their setup is very simple.  Coax comes in from outside straight into the back of their Technicolor CGM4331 (aka PW7) Panoramic gateway - no splitters.  From there it is Ethernet to the Xi6 receiver (no Wi-FI).  From there HDMI to the TV.  All wired end to end no wireless.

Any ideas?  Calling tech support I am having a hard time getting them to understand that the screen just intermittently goes black.  Thanks!