C# Accessing XML feed only works if fiddler is running

I am trying to understand why a simple call to a feed works only when I have fiddler open.

Ive looked at the below links, but none of the answers seem to apply:

My code is very simple, and as far as I can see, it should just fill the variable with the contents of the xml file:


  using (var client = new WebClient())
            {                    
                text = client.DownloadString(path);
            }

Note that this works perfectly if I am running fiddler, but fails with a timeout error (?) if I run it while fiddler is not running.

I can access the path to the xml file directly from my broswer - so permissions/access does not appear to be a problem either.

Does anyone have any idea why this might be?