macOS Profile Not Working on Disconnecting VPN

Normally I use a VPN and have configured a custom DNS to NextDNS in the VPN Wireguard client (which works except no way to add device name when IP4 enabled!).

But occasionally I disconnect from VPN so have also installed a macOS profile (generated using NextDNS website) but when I disconnect from my VPN the Mac reverts to the DNS as provided by my DHCP server NOT the profile.

I did have Next DNS configured on Mac settings but I'm keen to try and get device name into the logs - but it's all proving a complete nightmare.

Also my ISP seems to support IP6 but DNS queries seem to be forced to IP4 (UK BT!)