in case you’re making use of libvirt or Virtualbox, this won’t work For the reason that virtual NAT product has its own DHCP server that will get in the way. this means you’ll need to set up Static IP addresses https://macktechbiz.com/blogs/news/unleashing-the-power-of-micro-appliance-pc-firewalls-a-revolution-in-open-source-firewall-solutions-with-zenarmor-and-opnsense-support