Hi Leo,
When I try to connect to a PC that is about 100 km away, not that the distance really matters ;), I cant connect to the host (version 6.3).
You need to upgrade the Host to version 6.5 too. Always try to make sure that the Viewer and Host are the same version. There is backward compatibility , in theory, but you still should avoid relying on it all the time. It's better to upgrade.