Why would my C# app fail on this REST request but but works fine through a browser?

I have a C# app and I am accessing some data over REST so I pass in a URL to get a JSON payload back. I access a few different URLs programmatically and they all work fine using this code below except one call.

Here is my code:

 var url = "http://theRESTURL.com/rest/API/myRequest";
 var results = GetHTTPClient().GetStringAsync(url).Result;
 var restResponse = new RestSharp.RestResponse();
 restResponse.Content = results;
 var _deserializer = new JsonDeserializer();

where GetHTTPClient() is using this code below:

private HttpClient GetHTTPClient()
{
  var httpClient = new HttpClient(new HttpClientHandler()
  {
     Credentials = new System.Net.NetworkCredential("usr", "pwd"),
     UseDefaultCredentials = false,
     UseProxy = true,
     Proxy = new WebProxy(new Uri("http://myproxy.com:8080")),
     AllowAutoRedirect = false
  });
  httpClient.Timeout = new TimeSpan(0,0, 3500);
  return httpClient;
 }

so as i said, the above code works fine but a bunch of different request but for one particular request, I am getting an exception inside of the

 .GetStringAsync(url).Result

call with the error:

Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host

I get that error after waiting for about 10 minutes. What is interesting is that if I put that same URL that isn't working into Internet Explorer directly I do get the JSON payload back (after about 10 minutes as well). So i am confused at why

• It would work fine directly from the browser but fail when using the code above.
• It fails on this one request but other requests using the same code work fine programmatically.

Any suggestions for things to try or things I should ask the owner of the server to check out on their end to help diagnose what is going on?