I had same issue with just the ubiquiti on my local network at home when i was setting gear up. Never got to the browser page. Then i realized upnp wasn't enabled by default on these routers. So i figured out how to do the command line bs to enable it and then it went to the browser page like u describe and it all worked fine. It loads the ip address from service provider in browser window and seems to pick its own random port each time it connects. But now that I'm behind this second router its back to same error message where browser never even loads just like before. Same thing on mac, etc.