title: Explanation: The underlying connection was closed: The connection was closed unexpectedly
body: <p>There are so many questions about this issue but none has been able to address my issue specifically and I have yet to find any valid explanation of the error itself:</p>
  
  <pre><code>The underlying connection was closed: The connection was closed unexpectedly
  </code></pre>
  
  <p>In our situation we are making a call to a 3rd Party API via SSL. On my local PC I can connect to that API make a request and get a response back, but on an IIS Production server I get this error. The API is using OAuth to authenticate.</p>
  
  <p>What exactly does it mean. Is the request leaving our server and rejected by the remote server, or is it not even leaving our server and our system is preventing it from making the request. </p>
  
  <p><strong>Some more information incase anyone may know what the issue is:</strong></p>
  
  <p>No known changes to any networking, servers, routing, security (apparently)
  No code changes recently</p>
  
  <p>According to our own internal logging, the issue started off as an ocassional <code>403 Error-Forbidden</code> then we saw a number of <code>Cannot Connect to Remote Server</code>. Eventually it failed with <code>The underlying connection was closed: The connection was closed unexpectedly.</code> </p>
  
  <p>Can someone please explain what the actual error means? If anyone has experienced this in a similar situation and can shed some light, that would be greatly appreciated. </p>