My internet service has been intermittent for many months. My wifi works fine. It feels completely random. When I call service they just reboot the xfinity arris modem (which I can do myself). Then they check connectivity (or something like that) which shows everything is fine because the problem is intermittent. I'm not an expert but it feels like a wire short to me. The problem seems to be getting worse and my family is complaining. What can I do?