i agree. that and i've been getting a lot of protocol errors. i use zentyal as a gateway and i have any-to-any set from my isp(nat1) to ps3. which means i all ports are open. but i still have issues.
its part crytek and part player to player problem. start by making sure your router is configured properly.(port forward or dmz mode the ip address to your ps3). also make sure to make the ps3 ip address static. have your friends do the same.
but like i said mine is set right but i still have issues. but maybe it will you.