I only use openHAB app from local network. Direct out of wlan or with von tunnel.
If put local address in both fields (local and remote) the log is full of errors broken pipe.
So i just tried to use local address only and empty the field for remote.
No chance to clear : it always enters and trieing with openHAB cloud then.
If this address is in: there are other problems while connecting.
So i have now only the only chance to accept tons of broken pipe errors in log. App should able to work „local only“ 
enough for people with vpn