One of the things I need to catch up on is use of nmcli to manage
everything about the network interfaces on Linux machines. All the old
ifconfig stuff is really old.
Note that this does not come by default on Ubuntu Server so will have to be installed and activated:
sudo apt install -y network-manager
This is because since Ubuntu 18.04, the network configuration file has changed from interfaces to netplan, and you need to use apt install network-manager again modify /etc/netplan/00-installer-config.yamllike this:
network: renderer: NetworkManager
This allows the network configuration to point to NetworkManager,then > use netplan apply load this file. you can use nmcli device status check if the configuration is in effect