RBR750 drops connection about once / per day

RBR750

firmware version V4.6.8.2_2.1.9 

I've had a problem for at least 6 months, probably longer.  About once per day (give or take) my internet drops and it takes about 60 seconds to come back.  The facts do not add up, but suggest a router problem more than any other possibility.  Here are the facts:

• Xfinity cable modem in the mode that only provides internet access, not router service.  I think that's called "gateway" mode or "bridge" mode.
• Xfinity connected to Orbi router.
• Orbi router connected to a Netgear Switch.
• Almost all devices connect via Wifi except my own personal laptop, which uses a wired connection (to the switch).
• Internet works on all devices (except for the random drops).
• About one time per day (give or take), my personal laptop (wired) and my work laptop (wifi) lose network connection at the same time.
• My son's xbox and tv in the other room, do not lose connection.
• I checked the router logs today and at roughly the same time as today's drop, the log shows the router synchronized the time with the NTP server.

If this was an Xfinity modem problem, all devices would lose connection.

If this was an ethernet cable or laptop port issue, only my personal laptop would lose connection.

If this was an Orbi router problem, then all devices should lose connection.

I have two theories.  One is that I'm having an issue with either the Orbi base and my personal and work laptops are both connected to it, while other devices in the house are connected to the Orbi satellite.  Devices connected to the base lose connection, but those connected to the satellite keep their connection.  This theory has a big problem though.  I checked attached devices in the Orbi admin page and it doesn't show a single device attached to the satellite.  Everything says it's attached to the base (router).  This theory could still be the cause if, during the 60 seconds the base drops connection, most of the other devices are able to switch over to the satellite a continue operation but my personal and work laptops take longer to switch over.  That's far fetched, but not out of the question.

The second theory is that when the router syncs to the NTP server, my personal and work laptops take 60 seconds to sync up to the router but other devices don't care about the time.  I think that theory is also a bit out there, but I'm grasping at straws here.  Also, it's possible the sync is occurring AFTER the connection is restored.  Which means I'll always see that in the logs, but it doesn't actually matter.

My current investigation steps are to check the logs again the next time there is a drop and see if the network time synced.  I'm going to place a spare laptop in the room with the satellite and confirm it is attached to that satellite.  During the next drop, I want to run out to that room and see if that laptop has also lost connection.

During the next drop, I also want to check if I can still connect to the router admin page.  If yes, I want to check connected devices and see if they are all now connected to the satellite or are still showing a connection to the base (router).

Any other idea?

Thank you in advance,

Darren