If possible, can you check the output of logcat (grep for System.err, and tvm) after you process (Start RPC) or the RPC Activity appears on the screen?
One thing to double check: are all your devices on the same subnet, and are there any virtual machines involved in the process that would complicate the networking situation?
It shouldn’t affect this case, but you can also try updating the RPC app as there was a recent update.