How can i change the connection of my PS3 and Hughes to NAT2?

When I try Red Dead Redemption Multiplayer it gives me a warning about my connection being NAT3 and because of that i can only play if i invite my brother, so I was wondering how can I change the connection to NAT2, here is how i connect all i do is take the ethernet cord out of my PC and plug it into my PS3, i know the default setting is supposed to be NAT3, but i want to change it. to be clear I DO NOT USE ANY KIND OF ROUTER,WIRED OR WIRELESS, i am not yelling, just being clear, please help.