The strange thing is that the very same machines all connected concurrently using Ghost 8 without a problem. We've made no changes to the network setup whatsoever.
Is there a manual workaround for identifying individual machines?
In Ghost 8, the network service that manages the clients used the network adapter MAC addresses to identify them, but although this worked well in most cases there were a significant number of compatibility problems caused by software network adapters pretending to be physical ones.
So, in GSS2 we tried to use the special, guaranteed-unique ID created for the use of management software like GSS. Except that, as we've discovered, manufacturers aren't making this unique ID really unique either (and as well, there was a special-case invalid UUID that I didn't filter out, which is my fault).
It definitely sounds like it's the most likely cause of your problem, and you're welcome to try the fix I have. Unfortunately, there's no easy way to override this; you need an update to to the ngserver.exe code on your console machine, and right now to get hold of it you can get in touch with me at nigel dot bree at gmail dot com