So DR works for some time....then master stops seeing the node on the DR list?
Try this:
On the node: make sure there is ONLY ONE instance of the DR server (drserver.exe) running, and that there is ONLY ONE instance of 3ds Max running (the one spawned by the DR server).
On the master: make sure there is ONLY ONE instance of 3ds Max running.
If there is more than 1 DR server or 3ds Max running on any of the computers, various strange things may appear, including issues with the connection. We are aware of this limitation, and we are working on a solution, so that you would not be limited to just 1 3ds Max running on each PC (so that you can for example render in on Max and model in another).
I hope it's the solution. If not - we'll think of some other possible culprits.