DelphiDev01

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.