Whenever I bring up a new computer on my local network, I make sure it has a unique hostname. For the Raspberry Pi, you can do this with the rasp-config program.
If you have a halfway decent home router, you should be able to bring up your QnetGateway dashboard from any system on your local network using the url "<hostname>.local" where <hostname> is the hostname assigned to the system QnetGateway is installed. For example, I assigned "zumspot" to my Pi Zero W with ZUM board.
Then in a browser, I type "zumspot.local". No "http://", no "www.", just "zumspot.local" and the browser will query my home router and figure out how to get to my zumspot.
Tom Early