Badmoon I know Kain was having nat issues too and I told him I would look for a way to fix this. Check out this site. Find your router in the list, then select the Playstation Network and it will show you hoe to forward the correct ports. the other option would be is to set the IP of the PS3 in the DMZ which basically puts it outside the firewall.
https://www.portforward.com/english/routers/port_forwarding/routerindex.htm
https://www.portforward.com/english/routers/port_forwarding/routerindex.htm