Session Disconnected only over internet

I have PocketCloud installed on my Droid X and my Xoom. I am using Auto Discovery with VNC. Loopback is turned on. It works fine when my Droid X or my Xoom are connected to my wireless network. However, when I switch to my 3G connection my PCs still show but, when I select them it attempts to connect and then after about 60 seconds I get a session disconnected error.

Am I missing a setting or something?

Thanks,
Dan