The suggestions I can offer.
1. Put the router's power supply on a Uninterruptable Power Supply. They seem to be sensitive to power dips.
2. Connect directly and see if the dropout happens. Some ISPs are less than reliable.
3. Is this DSL? Double check those filters.
4. Try another make/model router.
I have a linksys BEFW22s4 ver.4 router with "latest greatest" firmware. I will be playing a game or surfing the internet and i'll be disconnected from the game server and the browsers will not be able to connect to the internet. All the computers on my home network will be disconnected from the internet. I don't get any kind of icon that tells me I'm disconnected like when I pull the cable out or something it just quits working. I then cycle power on my router and everything is back to normal.
I have called my isp and they tell me they don't support home networking yet they called me a few months ago and told me I would have to upgrade my firmware on my router.
I started noticing this soon after SP2 from windows xp. I have disabled the firwall in my OS. I have tweeked some of the security settings in my router and have not come up with any thing that works. I change one thing at a time and if it doesn't help I change it back. I went to Linksys and searched there online help and they tell me to clone the MAC address so I did that and upgrade firmware, I did that... I am stuck. Does anyone have any more ideas?