Thank you all for the help!

 I managed to fix the problem, and it was actually unrelated to the setup
 of networker or nmc.

 I looked up the java error and found I had to configure java for a direct
 network connection. The default was to use browser settings, which in this
 case means, use a network proxy.

 So, this is done using java's jcontrol tool, "General" tab, Network Settings.