You should check the ports of your router.
Please enable the following online ports on your connection:
TCP: 53, 88, 3074
UDP: 53, 88, 3074
For specific instructions on how to open your ports, please visit http://www.portforward.com/ or contact your router manufacturer.
If you still have this issue, you can try to delete all BF3 gamedata from your console (including all update data). As the gamedata includes several multiplayer updates, it might be that some of these data got corrupted during update process.
Cheers
Basti
