No @Hvergelmir, everything I wrote in this forum thread is rubbish. That’s because I don’t know much about Linux Networking.
However THIS here suggestion (also by me) seems very good to me, and even though I don’t know enough about Linux Network to suggest it, it has worked excellently at my setups (both linux servers and desktops, and also both snap and apt-based installations): A way to resolve container.lxd from host, in all cases