When I ran windows I had that problem, if what you're speaking of is not being able to join your pc dedicated server from your ps2 on the same network. I solved it by fixing the ps2's network address and making it the DMZ. To get your ping to show up, you need to set your router to respond to external pings (not wise to leave it that way though) If you port-forward to your pc you may not be able to talk to other players, so see if it works without.
This is all old news, but the idea that pc's can handle no more than 6 players is a myth. Mainly because most DSL lines have 256kbits of upload bandwidth, and though cable can go faster, it doesn't do so consistently. I've monitored the bandwidth used by players on my server, and for lag-free it works out to about 60kbits for the 1st, 58 for the second, a little less for each additional player. So if you have a better DSL line, for instance mine has a settled upload of about 690 kbits/s, and max of 896kbits/s, you can handle 10 to 12 with no problems at all.