Okays peeps, I got a problemo..well kinda!

I can play online games fine usually, Resistance online runs fine, Stranglehold too and the Burnout Paradise demo.

However, recently bought Unreal Tournie 3 and basically i keep getting disconnected after 5 mins. The error message tells me that I've been signed out of the PSNetwork, but this isnt the case cause when I quit the game, i'm still signed in!

I'm connecting wirelessly..using a Belkin router.
No problems with the other games, only Unreal Tournament 3.
Was configuring around with the port forwarding stuff, but no avail.
Not sure how to utilize the DMZ.

Came across some forums and someone suggested turning off my firewall which i did, and lo behold... i didn't get signed out anymore.
However, it's rather risky that i leave my firewall disabled like that, so it's at best only a temporary solution.
Any ideas?