To help effectively we'll need more information. What errors do you see when connecting? (journalctl -u NetworkManager -f) Are you using configurations provided by a commercial VPN provider? How are you loading the configuration into Network Manager? - nmcli connection import type openvpn file .... - Graphically using your desktop environment? (NetworkManager-openvpn-gnome?)
For example, I have issues with Private Internet Access' OpenVPN files on Leap due to the inline certificate revocation list they contain. Removing that configuration option allows them to connect.
