As mentioned above you need to enabled UPnP port forwarding if your router supports it.
If your router doesn't support UPnP you need to either manually trigger or forward the ports for the PSN/games _or_ you can give your PS3 a static IP and use that IP as a DMZ (once again if your router supports it).
I've just checked your router out online and it does support DMZs this would be the quickest and easiest option for you. You just need to set the DMZ IP address on your router. When you re-do the network settings for the PS3 you need to do manual (or is it advanced?) setup. Give it this IP address, fill in all other details manually and you should be good to go.