What router do you have? My old Linksys router had a setting I was unaware of, for a ridiculous period of time to "stay connected"... so I experienced intermittent disconnections. When I found it, I set it for 9999 days and my problem was solved. That was an old WRT54G though. I suspect you have a newer router with different settings.
Absent any useful info, I would just suggest reading all the settings in your router's setup for anything that could be causing a similar issue.
With your router identified, someone may come along and offer some good advice.
Good luck...