Go into your router config (if you do not know how go to start>run type "cmd" and then ipconfig. The number that is next to default gateway can be typed into your internet browser to access the router config)
In the router config possibly under firewall there should be a DMZ option. Enable DMZ and put in the ip address of your ps3.
Done.
Also everytime you start ur ps3 your ip may change. You can go to the network setup on the ps3 and set the ip manually so it always stays the same.
You could also just disables the firewall of the router as well.