The problem I have is pretty much as Titi described it.
My router has a setting called "virtual server" which allows you to open ports for applications to communicate with the internet through a specified port. AFAIK this is usual on all routers.
I'm using MegaGlest 3.3.6 on Windows 7. When I click on internet game> custom game Glest freezes and crashes badly without an error message. This only happens if the port Glest is using to communicate is blocked via my router setting. I only found this out by accident since the router setting is usually enabled and i have no problems.
I am only assuming that this has anything to do with Glest trying to listen to the blocked port, I don't have any knowledge of the actual code.