Explanation Box 1: iothub1 The Azure IoT hub is named iothub1. Box 2: azure-devices.net The format of the device connection string looks like: HostName={YourIoTHubName}.azure-devices.net;DeviceId=MyNodeDevice;SharedAccessKey={YourSharedA Box 1: device1 Device1 has a primary key of Uihuih76hbHb. Reference: https://docs.microsoft.com/en-us/azure/iot-hub/quickstart-control-device-dotnet