Если есть файл ovpn и вы работаете под операционной системой Ubuntu 18.04

You have to install a few packages first with:

sudo apt install openvpn network-manager-openvpn network-manager-openvpn-gnome

then, restart network-manager

sudo service network-manager restart

and try again. If it doesn’t work, then try logging out and back in, if not, then try rebooting.

Источник — https://askubuntu.com/questions/1014653/how-to-setup-vpn-using-an-ovpn-file