it is most likely the dynamic ip address renewing. which is a good thing! it keeps hackers out, usually.
unless you turn your router off overnight, which no one would do, the ip stays on the same address for a long time. Eventually the system will force a change but again unless you turn router off for a couple of hours at least it will happen out of the blue. and everything stops, resets, reboots. verizon doesn't care if it bothers you and there is really nothing you can do about it and ultimately it is a good thing for your system safety.
but try to ask them why or what is happening and you will get no answer. took me a couple of years to figure this out and several dozen phone calls and one intelligent computer savey rep who had the integrity to be honest.
anyways, that could be the reason