If your router is configured correctly and the host is running, are you sure that your players have the same version (possibly different license, but the same version number) of the program?
If this discussion gets much longer, I guess it should be held on the support forum of Fantasy Grounds.
What about anohter iCon for Gen Con
A virtual gaming table convention should be great also as a satellite event for Gen Con (or one of them). At least people there, here, and the industry too would be in the mood. There are the three-odd months between iCon and Gen Con ... ;)