I know that my problems stem from the fact I have far too many devices connected to the router in my old cable modem. I get cheap fiber at street level by a local company but it's delivered via an ancient coaxial cable to the apartment.
The provider I use is certainly not responsive to my questions. I've wanted to upgrade the old Technicolor device for a year now! However, Surf Internet does let me go on snowbird break for five months out of every twelve! And I want to just flip the switch when we return from winter and have my local network all come back to life.
Rather than going with a different modem and buying my own new router, I think I'll limp through this summer with a new wifi extender. I plan to put all the smart home devices on it and, hopefully, this will take the load off the present modem/router. I don't have any Internet dead spots as we've only 720 sq ft of floor space, but I need an extra SSID to offload at least 20 devices such as lightbulbs, VoIP, my printer and 3D printer, and the air purifier.
Amazon should bring me a TP-Link AC1200 WiFi RE300 tomorrow. Our travel computer is the only device capable of AX, so I'll be all set until our November departure. It is worth it to me to spend the Canadian $39 just to play.