Problem with disconnects/packet loss/high latency

Hello,

I am having a problem with random occurrences of disconnects/packet loss/high latency.  All of the above are currently happening during the overnight hours, the disconnects are nearly every night, at least once - but have previously had this happen at all hours of the day, with disconnections as frequent as every hour.  This has been going on for months, if not a year+ now, with varying frequency.  

When the disconnects happen, it is usually very temporary - things are back up and running within a minute.  In between disconnects, everything runs as normal.  Speeds are good, no complaints. 

I am down to running only my xb8 gateway and wifi, with about 15 connected devices at any one time.  Since this problem started, I have tried all sorts of configurations and new equipment, but nothing has had an impact.  For the last few years, I ran a rax80 router (in access point mode), attached to the xb8.  This was mostly very reliable.  I would have a random problem here or there with disconnects, but nothing like we have been having recently in the time frame mentioned. 

I recently replaced the xb8 with a new one - no change, still having the same problems.  I tried running the xb8 in bridge mode with a ubiquity UDR 7 - no change, same problems (the UDR 7 provided the logs with the packet loss and high latency messages).  I have checked all connections and connectors in the house, replaced any and all suspect wiring.  An extremely capable xfinity technician was here, and looked at everything, and said all looked good.  He changed a splitter or two, but that was it. 

I'm at a loss here.  When more frequent, the disconnections are extremely disruptive.   

I am more mechanically inclined than I am network/technology savvy.  Can you give me the basics on what to look at here? 

Thank you!