It can be that your router doesn’t support UPnP. Or that our UPnP doesn’t support your router :-). Anyway this shouldn’t affect your ability to connect, even from the outside. Many routers that don’t support the query for the external IP still accept the commands required to enable port forwarding. If not, you will have to configure the port forwarding by using the router admin interface. This is normally a Web application running at http://192.168.1.1.
This “gateway” GUI is a retrofit, intended to alleviate the annoyance of having to find and enter the IP by hand. We struggled to get NoMachine Anywhere ready for the release but it was not possible. We are going to roll out the mDNS integration, for now (also known as Bonjour in the Apple world), so that any machine will be automatically able to find the other machines on the LAN. And of course this will work on any OS. Not yet the “final” solution, but a small step in the right direction.