Like I said before, the firewall could be within your router. Looks like your router has a firewall: http://www.dsl-warehouse.com.au/p/dg834g
Did you try enabling UPnP within the router & then using the UPnP option within LW???

Did you try any other ports in the range that I mentioned before?

Here are instructions for port forwarding: Port Forwarding for the Netgear DG834G
There are no instructions for the v3, but the ones above should be fine.

You'll need to set up a static IP address first, there are instructions within that port forwarding link. LW's listening port, port in the 'manual port forward' box & port forwarded within the router's setup should all be the same number.