`scutil --nc start` not connecting PPPT VPN - OS X 10.11
Was running into same issue. Ended up going the AppleScript route:

tell application "System Events"
        tell current location of network preferences
                set VPN to service "UniVPN" -- your VPN name here
                if exists VPN then connect VPN
                repeat while (current configuration of VPN is not connected)
                    delay 1
                end repeat
        end tell
end tell


(From https://superuser.com/a/358663/17760)