title: Socket.io keeps polling to establish connecting
body: <p>I'm trying to setup a messaging application working with Socket.io.</p>
  
  <p>Currently we're facing an issue with setting up our application with a reverse proxy in the middle. When we run our application locally then we've got no problem but when putting the reverse proxy in between it keeps on socket.io keeps on polling. So it's  constantly polling and no data is flowing through the long-polling connection.</p>
  
  <p>Has anyone faced this before? What type of configurations have we missed?</p>
  
  <p>Edit 1:</p>
  
  <p>This is a screenshot from the socket io client logger
  <a href="https://i.stack.imgur.com/fXcn5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fXcn5.png" alt="socket io client logger"></a></p>
  
  <p>This is a screenshot from the network tab where it keeps polling:</p>
  
  <p><a href="https://i.stack.imgur.com/ge3zD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ge3zD.png" alt="network tab"></a></p>
  
  <p>Edit 2:</p>
  
  <p>We use socket.io in <code>polling</code> transport mode only. So we don't try to setup a real websocket connection.</p>