I'm running Troopmaster 2015 under Crossover 15.0 on MacOS 10.10.
Long story short, I've never managed to get DotNet to work. Basically, Troopmaster doesn't seem to be able to do ftp. It tries, and fails. (And generally leaves Troopmaster in a state where it won't respond to the keyboard, but hitting ESC generally fixes that.)
I tried it with the official Troopmaster DotNet site and with a private FTP site. Same response.
I'm able to do normal FTPs from the command line, so my router settings are probably correct.
If anyone has any suggestions, I'd love to hear.