So I've been struggling with this issue for the past couple of years. The modem would reset multiple times a day (6 to 10 times per day). After countless exchanges with customer support, I changed three modems (UPC Connect Box), I changed my wifi routers (I use the modem mode) without any improvements.
Then many months ago, the problem stopped and I was very happy to be able to enjoy uninterrupted phone calls, Netflix sessions and the occasional online game.
A few days ago, the problem surfaced again. The only thing that's changed is that the neighbours are back and they are the only other UPC subscribers in the building (we are only 3 flats and the third family uses Swisscom). Thinking back in time, they were here when the problem was occurring, and they were not when everything worked smoothly.
Has anyone got additional pointers I should give customer service to help them in solving this issue permanently? I'm asking because the technician visited us twice when I had the issue (in one occasion the modem rebooted in front of their eyes) but did not find anything wrong with frequencies, signals and the like. I don't think I can stand another fruitless visit...