OpenVPN: Unconnectable server with multiple (virtual) interfaces

If you are trying to run an OpenVPN server on a machine with multiple virtual interfaces bound to the physical interface that binds the OpenVPN server, you should always use the local 1.2.3.4 (with 1.2.3.4 being the IP you want to use for OpenVPN) keyword in the OpenVPN server configuration file.

Otherwise, the packets that arrive on 1.2.3.4 are returned through another virtual interface (I think the one with the highest ifIndex, although I can’t verify that in my current setup).

Typical symptoms are these:

• TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)


•  Initial packet from 1.2.3.4:1194, sid=c912ec05 45db03c6 but no packet returned from server to client