[CM1000 to Orbi Tri-Band WiFi 5] internet disconnecting

I've had my equipment for 3 years now, and recently my internet intermittently drops. Coax internet and paying for 1Gig (though rarely see anything past 750MBps). Coax is single line to outside box (except connection point in house of course). When it's working, the whole setup is fast, but in the last couple of months it's quit. One more thing about my network, I've got an unmanaged switch with 5E cabling to different rooms (5 hardwired items) and about 26 items on WiFi. I've not taken apart the network to pinpoint the problem because the time between dropping could be days if not a couple of weeks. I think it's the modem because usually I can still log into the Orbi where it tells me there's no Internet. Any ideas?