Comment 1 for bug 1508064

It goes further.

If the desktop/laptop only has IPv6 (no IPv4 connectivity) nm-openvpn tries to connect to the IPv4 host and fails, disregardless, that an AAAA record is available and reachable.

Essentially, nm-openvpn does not allow for tcp6-client or udp6-client to be configured or to be autoselected. If IPv6 connectivity is available and an AAAA record for the OpenVPN Server is in place, tcp6-client or udp6-client should be tried/initiated first with fallback to tcp-client/udp-client.

If no IPv6 connectivity is available, then trying tcp6-client/udp6-client is not needed.
If no IPv4 connectivity is available, then trying tcp-client/udp-client is not needed.

It has either to be autoguessed (like the Android OpenVPN app does) or be configurable. As it is now, nm-openvpn does neither.

ii network-manager 1.2.2-0ubuntu0.16.04.3 i386 network management framework (daemon and userspace tools)
ii network-manager-gnome 1.2.0-0ubuntu0.16.04.4 i386 network management framework (GNOME frontend)
ii network-manager-openvpn 1.1.93-1ubuntu1 i386 network management framework (OpenVPN plugin core)
ii network-manager-openvpn-gnome 1.1.93-1ubuntu1 i386 network management framework (OpenVPN plugin GNOME GUI)

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=16.04
DISTRIB_CODENAME=xenial
DISTRIB_DESCRIPTION="Ubuntu 16.04.1 LTS"