Internet dropping numerous times per day!!

We had fine internet until beginning of August 2020. Since then, it has been continual issues of dropped signal. Steps taken
1) Replaced router
2) Tried rental modem & Router from Xfinity
3) Purchased new modem 2 weeks ago
4) Three technician visits that included new cable line from box outside into our office
The signal seems fine when they are here and check with their meters. Unfortunately, its impacting our ability to work from home. Zoom meetings are regularly dropped, and VPN connections disconnects. The modem appears to restart or something. The drops last, on average, 5 to 10 minutes.

HELP!!!! We are losing it!