I just locked down my NC installation to support only TLS 1.3 and all desktop clients (v2.5.3daily-Win64) stopped working. All mobile apps and web browsers work perfectly.
Wireshark shows the desktop clients send Client Hello packets advertising TLS 1.2. The server then sends a fatal “protocol version” alert and gracefully closes the session before any TLS handshake occurs.
When should we see TLS 1.3 support?