Check these options: If LW Will Not Connect (click on the blue link)

Oh, in actual fact the Netgear does have a NAT protection, which in some ways behaves like a firewall. Netgear's devices have UPnP turned on by default, and although most of their models work well with UPnP, occasionally they do not.

If you wish to try port forwarding the Netgear, instructions are here:

1. Setting up a static ip is the first & most important step: How to set up a static IP address on a Mac OSX 10.4.

2. Port Forwarding for the Netgear WGR614v7. To get to the LW settings for OSX: Command & Comma keys is the keyboard shortcut ⌘ ,
(Command & comma keys are shortcut to preferences for most OSX programs. )

Port forward both TCP & UDP.

Which port to use? Port 6346 is the default port, however any in the range of 49152 - 65535 are also good to use because they are not officially used by any other program & are generally the last to be blocked by ISP's.