Connect to Azure IoTHub via TMS MQTT

[DelphiDev01 0]

Please advise what I'm doing wrong here.

 

I'm trying to connect to Azure IoTHub via TMS MQTT and every time get "Connection lost". I tried both methods: by using certificate and by connection string.

For instance my code to create a client with using a certificate:

  FMQTTClient := TTMSMQTTClient.Create(nil);

  FMQTTClient.BrokerHostName := Format('%s.azure-devices.net', [FIoTHubHostName]);
  FMQTTClient.BrokerPort := 443;  // also tried 8883, got "csConnectionRejected_ClientNotAuthorized"

  FMQTTClient.ClientID := FMyDeviceId;

  FMQTTClient.OnConnectedStatusChanged := OnConnectedStatusChanged;
  FMQTTClient.OnPublishReceived := OnMessageReceived;
  FMQTTClient.OnSSLIOHandlerConfiguration := OnSSLIOHandlerConfiguration;

 
  FMQTTClient.KeepAliveSettings.AutoReconnect:= True;
  FMQTTClient.KeepAliveSettings.KeepAliveInterval := 30;
  FMQTTClient.KeepAliveSettings.KeepConnectionAlive := True;

  FMQTTClient.Credentials.Username :=
    Format('%s.azure-devices.net/%s/?api-version=2020-09-30', [FIoTHubHostName, FMyDeviceId]);

  // Password is not needed for client certificate authentication
  FMQTTClient.Credentials.Password := '';

  if not IdSSLOpenSSLHeaders.Load then
    raise Exception.Create('Failed to load OpenSSL');
  if not IsOpenSSL_TLSv1_2_Available then
    raise Exception.Create('TLSv1_2 is not available');

  FMQTTClient.UseSSL := True;

 

And code to configurate SSL connection:

procedure TMQTTClient.OnSSLIOHandlerConfiguration(ASender: TObject;
  var ASSLIOHandler: TIdSSLIOHandlerSocketOpenSSL);
begin
  ASSLIOHandler.SSLOptions.CertFile := FCertFileName;    // Device certificate
  ASSLIOHandler.SSLOptions.KeyFile := FKeyFileName;      // Device private key
  ASSLIOHandler.SSLOptions.Mode := sslmClient;
  ASSLIOHandler.SSLOptions.Method := sslvTLSv1_2;
end;

 

But every time I get 'ConnectionLost'. Any thoughts, guys?

 

Appreciate any help.