L2TP
Setting up L2TP VPN Client on Ubuntu (Gnome Desktop)
sudo add-apt-repository ppa:nm-l2tp/network-manager-l2tp
sudo apt-get install network-manager-l2tp network-manager-l2tp-gnome
Ref: https://www.hostens.com/knowledgebase/how-to-configure-l2tp-vpn-on-linux-ubuntu/