When you don't want a simulated device to directly connect to a server, utilise the NONE protocol.
There are certain cases when the device you are simulating does not need to directly communicate with a server. It could be that you are just testing the functionality of the device, or it is an auxiliary device that connects to the server via a Gateway device. In these cases, you can use the NONE protocol which does not create a direct connection to any server.
Loopback: The loopback setting allows you to receive whatever payload the Sender function sends into the Receiver function. This can be useful for testing the functionality of a device.