I'm not sure of the nature of this problem but I will explain what I can:
Two of us in the same town, more or less. I am using a Windows 7 machine, the other guy a recent-model Apple laptop. If I set up the jam, I can hear both of us but I got kicked off the server every three minutes due to an “authentication” error and had to keep re-entering my credentials. The other guy could join but could not hear me at all (mute not checked). When he tried setting up the jam, it never appeared on my jam list, although it showed up on his.
Any advice on how to go from this to something workable would be welcome.