I agree with the OP: His external addresses, routes from his internet provider, etc have nothing to do with this problem. He is trying to connect using internal addresses only.
Meanlean: I've only recently had this happen to me once: My remote (EOS Remote, which is similar to JRemote) wouldn't connect. Restarting MC made no difference. Restarting EOS made no difference. I finally figured it out: Something was wonky with the networking on my Mac. I turned off Wifi, turned it back on, restarted MC, and *boom* it worked first time.
So that's my suggestion: Turn wifi off, then on. Restart MC and try again. If that still fails, I would reboot everything: Mac, Router, Ipad. Then try again.
Good luck!
Brian.