An error has occurred during a TLS handshake.

WebSocketSharp.WebSocketException: An error has occurred during a TLS handshake.
---> System.IO.IOException: The authentication or decryption has failed.
---> Mono.Security.Protocol.Tls.TlsException: The authentication or decryption has failed.
  at Mono.Security.Protocol.Tls.RecordProtocol.ProcessAlert (AlertLevel alertLevel, AlertDescription alertDesc) [0x00000] in <filename unknown>:0
  at Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult) [0x00000] in <filename unknown>:0 \r\n  --- End of inner exception stack trace ---\r\n  at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult) [0x00000] in <filename unknown>:0 \r\n  --- End of inner exception stack trace ---\r\n  at WebSocketSharp.WebSocket.setClientStream () [0x00000] in <filename unknown>:0 \r\n  at WebSocketSharp.WebSocket.doHandshake () [0x00000] in <filename unknown>:0 \r\n  at WebSocketSharp.WebSocket.connect () [0x00000] in <filename unknown>:0
TlsHandshakeFailure

I am receiving this exception when connecting to a TLS server using the Unity platform. Connection works fine if I disable TLS or connect via another platform.

Start by reproducing the TLS connection on Unity and a working platform, then trace the failure through WebSocket.setClientStream() and WebSocket.doHandshake() using the provided stack trace. Compare the platform-specific TLS behavior and document a reproducible cause and verified resolution.