netplan(.io) is an abstraction layer on top of either NetworkManager (GUI installs) or systemd-networkd (servers/non-GUI) and is not really needed except as a convenience for Canonical's own designs for automated mass deployments especially linked to cloud-init. Under the hood it just converts its YAML configuration files into the syntax for the underlying actual network management tool.
For NetworkManager it'll write the config file to /run/NetworkManager/system-connections/ and for networkd to /run/systemd/network/ on EVERY boot since /run/ is a tmpfs (file-system in RAM).
For almost all servers, and most workstations, netplan is an unnecessary indirection since most hosts (including containers) have pretty static network configurations that only require writing once (to /etc/NetworkManager/system-connections/ or /etc/systemd/network/ ).
nmcli is the NetworkManager command-line tool. There is also nmtui for a text user interface. These are terminal alternatives to the GUI applets such as nm-applet (network-manager-gnome) or plasma-nm for KDE.
networkctl is the CLI interface to systemd-networkd. There is no widely used GUI interface to it (yet).
For NetworkManager it'll write the config file to /run/NetworkManager/system-connections/ and for networkd to /run/systemd/network/ on EVERY boot since /run/ is a tmpfs (file-system in RAM).
For almost all servers, and most workstations, netplan is an unnecessary indirection since most hosts (including containers) have pretty static network configurations that only require writing once (to /etc/NetworkManager/system-connections/ or /etc/systemd/network/ ).
nmcli is the NetworkManager command-line tool. There is also nmtui for a text user interface. These are terminal alternatives to the GUI applets such as nm-applet (network-manager-gnome) or plasma-nm for KDE.
networkctl is the CLI interface to systemd-networkd. There is no widely used GUI interface to it (yet).