title: Why "(502) Bad Gateway" error happen?
body: <p>Windows 7 SP1.<br>
  Domain network.<br>
  .NET Framework 4.6.1. </p>
  
  <p>All my Internet browsers have configured proxy settings for Internet connections (it works fine). </p>
  
  <p>I need to download file from Internet. I configure <code>WebClient</code> for it will read proxy settings from default Internet browser and use credential of current process and I expected these conditions are enough for successfull downloading. But I get the exception (look the comment in my code):</p>
  
  <pre><code>static void Main(string[] args) {
      String file_name = Path.GetRandomFileName();
      String full_path = Environment.ExpandEnvironmentVariables(
          Path.Combine(@"%LocalAppData%\Temp", file_name));
  
      using (WebClient client = new WebClient()) {
          client.Credentials = CredentialCache.DefaultCredentials;
          //client.Proxy = WebRequest.GetSystemWebProxy();
          var proxyUri = WebRequest.GetSystemWebProxy()
              .GetProxy(new Uri("https://yadi.sk/i/jPScGsw9qiSXU"));
  
          try {                    
              client.DownloadFile(proxyUri, full_path);
          }
          catch (Exception ex) {
              // The remote server returned an error: (502) Bad Gateway.
              Console.WriteLine(ex.Message);
          }
      }
      Console.WriteLine("Press any key for exit.");
      Console.ReadKey();
  }
  </code></pre>
  
  <p>What I did wrong?</p>
  
  <p><a href="https://i.stack.imgur.com/Av9D9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Av9D9.png" alt="enter image description here"></a></p>