I currently use TinyWall Firewall, it works very well, it’s small/portable, no complaints I even donated to the Dev but I would really prefer open source, also it needs to be user friendly like TinyWall so my non-tech family members can/will use it like they do with TinyWall.
I haven’t had that happen unless my gateway or DHCP server changes, but on a server wouldn’t adding the rules to both public and private profiles solve that too?