Problem scenario
You have a Linux server with the openvpn binary command installed. You try to start the OpenVPN client service. You see this message: "TLS Error: TLS key negotiation failed to occur TLS handshake failed."
What should you do?
Solution
Reinstall and reconfigure the OpenVPN server. Just completely start over.
You may want to try this: https://www.cyberciti.biz/faq/howto-setup-openvpn-server-on-ubuntu-linux-14-04-or-16-04-lts/