If you've opted out of netplan, then you need to configure one of systemd-networkd or NetworkManager manually (on server, NetworkManager is only present if you've installed it).
I personally used to be opposed to netplan but I had to do some very esoteric network configuration which was super easy with netplan.
Unless it still insists on realizing all state or no state, I think I still prefer the things doing the work for/underneath Netplan
To your point, esoteric configurations. Netplan is all or nothing: done improperly, it can more easily break the whole house of cards.
It tries/applies everything... where the others allow more utility