I too seem to be having the same problems discussed within this thread. Here's my situation... I am currently connected to my home wi-fi service. My remote access works with no problems. The program finds my folder and all the movies within that folder. As soon as I connect to my iTouch to a VPN client, the program no longer can find my folder. I am continually getting a "tracker service seems to be down" message. Now, I do know that other people that I work with have been able to connect to their Air Video servers through this same VPN Client so I don't believe there is a firewall blocking access. What else could be the problem? Could there be an issue with connecting to my work VPN while still using my home wi-fi? I have not tried connecting through my work wi-fi, but I don't believe it would make a difference. However, what do I know right? Ha Ha.
I have also set up port forwarding as described. Upnp and NAT are both enabled. Is there something else I should be doing?