I have 2 ps3 systems and play call of duty modern warfare 2, one will connect to serverr but the 2nd ps3 won"t?

i have 2 ps3 systems, i use one and my roomie uses other. we both play call of duty modern warfare 2. one will connect to server and the other keeps saying updating rank, trying to find matchmaking server. I have a wireless router that both operate on. i have cable internet too. any ideas or anything i can do to fix so we can both connect at same time? sometimes it will connect but usually takes from 30mins- up to 3 hours and sometimes it will not even connect, tried resetting system and sendin invites, that dont work either