My question is a follow-up on the answered question here: OpenVPN issue - TLS key negotiation failed to occur within 60 seconds
I do not have enough reputation points to comment on the original discussion.
I am using UDP on a OpenVPN server setup on a Raspberry Pi device (via PiVPN).
I am in a remote location, and I am able to successfully connect to the server with the OpenVPN Connect Android app on a mobile device.
However. when I try to connect to the same server (from the same remote location, on the same remote network) from a Debian desktop device, using openvpn, I am presented with the TLS key negotiation failure issue:
tail -n 10 /var/log/openvpn.log:
Dec 18 14:58:06 server-pi ovpn-server[563]: xxx.xxx.xx.xxx:38496 TLS: Initial packet from [AF_INET]xxx.xxx.xx.xxx:38496, sid=7f641c7e f5ae9f48
Dec 18 14:59:06 server-pi ovpn-server[563]: xxx.xxx.xx.xxx:38496 TLS Error: TLS key negotiation failed to occur within 60 seconds (check your network connectivity)
Dec 18 14:59:06 server-pi ovpn-server[563]: xxx.xxx.xx.xxx:38496 TLS Error: TLS handshake failed
Dec 18 14:59:06 server-pi ovpn-server[563]: xxx.xxx.xx.xxx:38496 SIGUSR1[soft,tls-error] received, client-instance restarting
If this is indeed an issue with using the UDP protocol over TCP, why does the OpenVPN Connect Android app have no such difficulty when the Debian desktop client does? What is the difference?
