Bizdude Win XP has its own firewall. Did you disable it or not do anything. See Firewall configuration instructions (click on link)

I didn't notice any mention of UPnP capability for your Aztech DSL305EU which means you might require port forwarding. Particularly if you use it in ethernet mode.

There's 3 steps to port forwarding. And the setting up of a static ip is the 1st you must do & must do properly for this to work at all!
The steps:

1. Set up a Static ip

2. Forward port 6346 following these instructions: Guides for the Aztech DSL305EU (also includes instructions for setting up your static ip!

3. Within LW: Manual port forward instructions & sample image & 2 posts after that.