NAT 1 is direct connection from modem to PS3, nat 2 is using router.
Just finished my Class B just now...I have to say I am very impressed with the AI this time. Unlike previous games, GT5P have a decent AI that tries to block and ram you off the tarmac. Something which is welcomed

and the online..uh okay.
I had problem connecting the game. I faced error 11:00000 Matchmaking something. Then I disabled the uPnP from PS3's network settings, and the thing went fine. This is what I noticed:
1. Lag (cant really blame PD, its our Malaysia Boleh ISP

)
2. The online lobby is pathetic.
3. No friends' list
4. Matchmaking? If I were the groom, then they would wed me to a witch.
In short, PD should head to Santa Monica and learn a thing or two about online gaming from WARHAWK team. The Japs may push PS3 to the edge, but they suck in online gaming like this.