Direct competitor unifi provide multiple ways for this already.

@Clive_A Unifi's default behaviour for VPN client since a few versions back is to drop any routed traffic if the VPN goes down, you can also set in the policy routing to route specific IP to the VPN...

Is it possible to add a simple killswitch if a vpn goes down ? For example if i route only specific machines via the vpn, if it goes down i don't want those machines to have any external access....

Appears to not be possible to route only specific machines over the wireguard vpn rather than the whole network, is this possible to add ?