Thanks SolMorande, it works perfectly now! Though we don't have ATT, so I wonder what that was about... and we could connect to the internet in everything else, just not the PS3.
You do it on your PS3. On the XMB (the main menu) go to Settings->Network Settings->Internet Connection Settings. Hit X when it tells you what you're about to do. Then when it says "Select a setting method." choose "Custom". The system will probably prefill all the next screens with the settings you already have so go through each one of them until you get to a screen that says "DNS Setting". Instead of Automatic, choose Manual. Then you will come to the screen where it will ask you for a Primary and Secondary DNS and that's where you put those numbers down (18.104.22.168 and 22.214.171.124) then you can continue on to the end and it will test the connection and see if that worked.
worked on mine, thanks solmorande!
btw i have ATT and i hate them now.