Yes, your router most likely will have an internal NAT which behaves like a firewall in many ways by helping to block out unwanted traffic.

Can you find out the model of your 2wire device?

BTW you should be able to log into your 2wire device via your browser. Replace the entire address line, & type in 172.16.0.1 & that should take you to the router's control centre. Else try the ip of 192.168.1.254 in the address bar of your browser.

Knowing which model you have will help us to give you specific instructions on how to forward a port. After looking at the 2wire port forwarding instructions, it seems it actually requires program specific information to be included in the firewall rule. So chances are your 2wire is one of the main issues behind your connection problems.