RPC 1723 error can be occur when the RPC server you registered is stuck in a RPC function that the client is calling. If the 1723 error occurs check all the function that the RPC client calling is ended in the last time you have used the same server. We can check this by monitoring the RPC server listen thread(the thread that  you call RpcServerListen function) returned successfully after calling RpcMgmtStopServerListening call. 

Note : Even if you set DontWait = FALSE in RpcServerListen function RPC server might be stuck in the last call that it had.