It’s currently not possible to automatically enable/disable broadcast or permit/deny incoming connections when you move to different location.
This can be archived with help of system scripts where you can detect changes in network interfaces and reconfigure NoMachine configuration files.
To filter incoming connections you can use a system firewall or prepare a custom script that NoMachine will executed before login – ‘UserScriptBeforeLogin’. Please take a look at article about custom scripts:
https://www.nomachine.com/FR01M02857