I try to call some HTTP GET calls to the device twins of the MS Azure IoT Hub.
As you can see the GET call results in an unauthorized IoTHubUnauthorizedAccess error code.
I generated the token for the authorization header with the Azure Device Explorer as you can see in the picture below.
Anyone any idea about this? I already searched here, and the only topic did not help me.
It seems you are trying to access the Device Twins from a "device" (as you are using a SAS Token generated from a Device ID/Key pair) using REST APIs. This cannot be done as the interaction with Device Twins for "devices" is done through MQTT, not through HTTP (see links below for docs on IoT Hub endpoints and twins). I recommend you take a look at the Azure IOT device SDKs if you want to work with device Twins from a device. If you want to learn more about using MQTT, you can read this.
However if you want to work with device Twins from the backend perspective (as in using a backend app that sets desired properties for devices, reads devices reported properties and work with tags) then you need to use a SAS Token generated from one of the IoT Hub shared access policies name/key (not Device credentials). Try generating a SAS Token using the same Device Explorer tool, but on the "Configuration" tab for this.
Some docs on Device Twins that can help make all this clearer:
