Not active on PSN = Log out?

My friend is having trouble with his internet on his PS3. I set it up the same as mine, mine is perfect and nothing really wrong. His router isn't even that far, mine is farther too. Anyway it is so weird, it would log him out everytime he was at XMB for about 3 minutes. I told him it cuts him of when hes not active on the internet because in game when hes playing online, its fine, but its so annoying how it would cut him off just by waiting in the XMB or not being "active" on PSN. Any tips? I'm not to advanced in computers by the way, but I know a lot.

I switched media sharing off a while ago..when he first got it like mine.

Is it a Linksys router?

Try changing the wireless channel and make sure firmware is up to date.

Run a speed test on your computer.

I used to be with an ISP who only gave me about 7 MB on my connection. I would constantly get logged out every 10 minutes and when I let my console linger, I would log out every 2 or so minutes.

Switching to Comcast gave me 24MB and I never get logged out anymore.