Just downloaded v 2.2 (November 23rd, 2015) for which I hoped connection problems with Prepar3D V.3 were solved. Unfortunately for my situation this was not true.
This is how I can reproduce it: - start up simserver - startup P3D with a loaded PMDG flight - test working remote CDU -> OK - reset the scenario or load a new one (any major change in the current scenario will invoke this). - the remote CDU will display a lost connection - when P3D has been restarted with the selected scenario a display appears on the remote CDU, but this is not in sync with the CDU in the sim. No keys will operate on the remote CDU. The problem is only solved by completely exit P3D and restart from scratch.
Jelle