Not sure if I understand the issue correctly, but I think the app detects whether port forwarding is set up on your network, and if so, it will modify the local IP to external IP, so that you can remotely access the controller. Usually the external IP works just fine if you are local on your network — but we did find that some routers block accessing the external IP when you are on the local network (i.e. a request coming from within the network that tries to access the external IP). This might be your case.