I have played ps3 online in this manner before, so I know it can be done. I was playing Resident Evil 5 online just last week. I have a laptop with a wireless internet air card connected to a ps3 via an ethernet cable. A few days ago, I run the connection test and the ps3 says failed to find IP address. Which is a load of crap because I added it manually. Also on the laptop it says "limited or no connectivity" in the network connections menu. Whenever I try to renew the IP address it says "failed to renew IP address contact the person who manages your network". Like I know who the hell that is or how to reach them.

Ask your broadband provider to test your lines over the phone. If all checks out ok then call whoever makes your router and tell them the problem you are having. Iron Sharpens Iron.