MS tells all the time, that it is possible to choose between AMQP and HTTP in their IoT-Hub...
But I can't find anywhere how that shall work.
I forget to mention, that I've got a solution for the client:
DeviceClient.Create(iotHubUri, new DeviceAuthenticationWithRegistrySymmetricKey(deviceID, deviceKey), TransportType.Http1);
But I don't know how to change the cloud-server
You don't need to change anything service side, just your client change will be sufficient.
Your client software design will need to change depending on the protocol. For example for cloud to device messages you'll need to poll to receive messages. See the section "Choosing your communication protocol" in the Microsoft Azure IoT Hub developer guide.
Also currently there is an issue with cloud to device messages with Http1 protocol in that the message is marked as Rejected whether CompleteAsync() or RejectAsync() is called. For updates on when this will be fixed please see this issue on github.
