C7000v2 disconnection issues

I installed a C7000v2 early January this year. Worked like a charm until last week. For the last week I have been getting almost hourly disconnections which usually last for about 3 minutes. No reboots necessary. Connection reestablishes on it's own. Called Netgear tech support about a week ago and did some trouble shooting. Tech told me that some downstream bonded channels were out of range and to call ISP and have them fix it.

Called xfinity and told them what Netgear said had to be done and within 2 hours all channels within range and have stayed in range for the last week. All were between -1 and +1 but problem continued and that did not fix it.

Called xfinity and had tech come out 2 days ago. He checked ALL the cables from the box outside that leads to the house wall and to the attic and back to downstairs to the outlet on wall that goes to the modem and said all signals measured fine.

I called Netgear again today and told them all that had been done from fixing the power on downstream bonded channels to checking all cables. He had me read him the event log and he pointed to following error in the log:

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=redacted;;CMTS-MAC=redacted;;CM-QOS=1.1;CM-VER=3.0;

He said the T4 time out points to cable issue so I am at a loss because the xfinity tech told me all cables good. He was pretty thorough. As I mentioned he even went up to the attic. No splitters anywhere either.

He also sat on the cable box in my front yard for about an hour monitoring the line trying to see if any odd signals coming in and he couldn't find any issues at all as far as signal or cables.

What to do?

Any suggestions are welcome. Thanks