I clean installed kubuntu and tried to add a vpnc vpn connection and all my settings are correct, but nothing happens when I click connect on the vpn in the 'networks' popup from the taskbar. The problem is that I hadn't installed vpnc yet. But I only knew this because I know the command 'journalctl -u NetworkManager.service'. I think there should be a notification or something from the Networks popup that at least reports something along those lines instead of just doing nothing. last line of 'journalctl -u NetworkManager.service': May 25 12:25:10 lappytappy NetworkManager[866]: <info> [1527276310.8979] audit: op="connection-activate" uuid="0940d836-8d01-459f-907d-59c67b9d8619" name="my_vpn" pid=23878 uid="0940d836-8d01-459f-907d-59c67b9d8619" name="cyrus_science" pid=23878 uid=1000 result="fail" reason="The VPN service 'org.freedesktop.NetworkManager.vpnc' was not installed."
I'll try to fix this for Plasma 5.14. I now noticed there are appstream metadata installed for each NM-vpn plugin so we can use it for checking their existence like we do in case of our vpn plugins.
*** This bug has been marked as a duplicate of bug 390133 ***