VDS VPN won't let me join anyone!

[RapidMods]

I recently made a VPN off of. Debian 8 VDS server. What I wanted to use this for is to play my ps3 on the vpn. I setup everything and im able to connect and use it on my computer and I can connect to ps3 online. But on bo2 i get a moderate nat type, and out of the 7 people I tried to join 0 were successful. I can't join any lobby or anything but I am connected and online. Does anyone know how to change to an open nat because on a moderate I basically can't do anything.

(Im using openVPN to connect)