service openvpn restart

Redirecting to /bin/systemctl restart openvpn.service
Failed to restart openvpn.service: Unit not found.
Try:

systemctl restart [email protected]

"server" may be name of the config file in $ ls /etc/openvpn -l|grep conf
mine was server.conf

Even if systemctl command return no result, service was restarted, verify:

systemctl status [email protected]