The new PSK protocol cannot run under an SSL terminating proxy
When running under a proxy which terminates SSL, ocserv doesn't have access to the original sessions, and thus cannot generate any keys to use under the DTLS PSK session. That currently causes a crash on the handling client, but even if that was fixed with 9938056f6cc070364cecf6af0a57a95499a54fde it does not address the underlying issue. The new protocol should be able to be used under an SSL terminating proxy.