Xamarin UI Test sometimes fails to start

Times from times when we try to run our Xamarin UI Tests our app/test fails to start with the following error:

System.Net.Http.HttpRequestException : An error occurred while sending the request
  ----> System.IO.IOException : Unable to write data to the transport connection: The socket has been shut down.
  ----> System.Net.Sockets.SocketException : The socket has been shut down

What is happening? Here is my environment:

• MacOS High Sierra
• Visual Studio for Mac 7.6.1 (Build 9)