iXtazze who is your OpenVPN provider? I have the same problem as you do. Have you found a solution? I always have 1 or 2 bars with COD Online Multiplayer and a Moderate NAT Type. Port Forwarding all the Ports on my router for that game and PSN according to Portforwarding.com did not work. but since my nat type is still moderate is the only reason i say that portforwarding did not work. (should i turn off UPnP on PS3? Do i also have to turn off UPnP on router?) Also I tried finding my OpenVPN's DNS Server number and entering that ip number into my router under DNS Server1, then also entering that number on the PS3 under network settings. ( in the same place where you set your static ip if you try to do portforwarding.) that didnt work and neither did using DMZ instead of Port Forwarding...
I think it really is all about Ping and you just gotta get lucky - or get some homies who will let you Host all the time?