The "default bionic install" uses only netplan yaml and /etc/systemd/network/ is empty.
If I switch to systemd.network style, I have to create config files from scratch anyway and then this KeepConfiguration helps. (Of course I do not need to keep the netplan yaml after enabling systemd-networkd, my remark for having the IP configuration in two files was wrong)
Using '/etc/systemd/network/10-netplan-ens160.network.d/override.conf' with KeepConfiguration works perfectly the same.
The "default bionic install" uses only netplan yaml and /etc/systemd/ network/ is empty.
If I switch to systemd.network style, I have to create config files from scratch anyway and then this KeepConfiguration helps. (Of course I do not need to keep the netplan yaml after enabling systemd-networkd, my remark for having the IP configuration in two files was wrong)
Using '/etc/systemd/ network/ 10-netplan- ens160. network. d/override. conf' with KeepConfiguration works perfectly the same.