title: How to diagnose slow HTTPS requests from Web API
body: <p>I have a Web API (ASP.NET Core 3.0, IIS 6.2) on Windows Server 2012 R2. When it's making an HTTPS request to an external SOAP API, I get a responce with code 500 after 20 seconds. My API wrote in a log:</p>
  
  <blockquote>
    <p>The operation timed out</p>
  </blockquote>
  
  <p>Tail of an exception stack trace:</p>
  
  <blockquote>
    <p>at System.Runtime.AsyncResult.End[TAsyncResult](IAsyncResult result)\r\n   at System.ServiceModel.Channels.ServiceChannel.SendAsyncResult.End(SendAsyncResult result)\r\n   at System.ServiceModel.Channels.ServiceChannel.EndCall(String action, Object[] outs, IAsyncResult result)\r\n   at System.ServiceModel.Channels.ServiceChannelProxy.TaskCreator.&lt;>c__DisplayClass1_0.b__0(IAsyncResult asyncResult)\r\n--- End of stack trace from previous location where exception was thrown ---</p>
  </blockquote>
  
  <p>I repeat my API's request from the same server to external one by SoapUI. It's successfull after 2-3 seconds. Also my Web API works from my another server.</p>
  
  <p>Unfortunatelly, I don't know how to get a reason of the problem. Can you give me any idea, please?</p>