This used to drive me fucking barmy at my old flat, I had the exact same issue, but it would happen every 3 or 4 days, if I didn't do a full power down and up of my router the internet would start randomly dropping out for 30 seconds or so. Not enough to be noticeable if you were just web browsing, but enough to kick you out of a online game or such. I was on Virgin Media back then, but due to the lack of service to my new place, I've settled with plusnet 80mb fibre; the issue still occurs, but it's much less frequent, I'll only need to reset it once a month. Anyway glad to see you mention it, because I've constantly been questioning my network in my head trying to figure out what could be the cause, and whilst I've always suspected it was the router / line, it's difficult to prove.