You want to exchange it for another model or make if Linksys doesn't offer a fix. I haven't seen this issue so I have no cure.
Bob
I am having issues with connectivity through my Linksys BEFW11S4 router, and the router seems to be fine. Specifically almost any standalone software client I run that connects to a remote server disconnects frequently, after a few minutes. Downloads tend to freeze in the middle. My instant messenger software has trouble staying online, and it disconnects and reconnects me every time I send a message. Web pages take ridiculously long times to load.
When I connect my computer directly to the cable modem, all of these problems go away. This points to a router issue, you would think, right? I have upgraded my firmware, with no effect. I have replaced the cat 5 cable that runs from the cable modem to the linksys router with no effect. Just today I borrowed a friend's IDENTICAL Linksys BEFW11S4 that is confirmed to be in working condition. There was a slightly noticeable improvement, but I'm still getting all the same problems. I also upgraded his firmware as well. Most recently, I've tried having my router clone my computer's mac address, but that doesn't help either.
My question is: Is there some kind of setting in the router management screen that I can/should change? Could this be a comcast problem in some way? I'm very frustrated that I can only use my internet service when my roomate is not home, if anyone has any ideas I would greatly appreciate it. Thanks.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic