Whenever I play on my xbox in my bedroom, I can play online without any problems whatsoever. I never get disconnected, and lag is never an issue. Keep this in mind.
However, I have another xbox in my basement (I bought it 2 months ago), but whenever I try to play it, I get disconnected from xbox live after playing for 5-10 minutes. This problem started happening about 2 weeks ago. Prior to that, I had no problems playing online. I haven't changed any wireless settings on my xbox or my router. I didn't really care too much about it, since I could play on the xbox in my bedroom. (by the way, I keep my profile on my USB stick) The problem happens with every game I play. Call of duty (MW2 and Black Ops), NHL 11, GTA 4, etc...
But then today, I downloaded Age of Empires Online (for the PC, it's a free game), and I logged into my xbox account in order to play. The same problem happened. After 5-10 minutes, I got disconnected. I kept on logging in, but after 5-10 minutes, it logged me out again. It's not my firewall, since I turned it off after this started happening, but it kept on logging me out. And my PC doesn't have a problem connecting to the internet.
I really don't know what to do about this. I don't get why this problem doesn't affect the xbox in my bedroom, but it affects the xbox in my basement and my PC.