title: Can not access GCE instance via external IP
body: <p>I created a instance on GCE and started a python Flask hello-world script running on port 5000. Port 5000 is whitelisted in firewall settings.</p>
  
  <p>Pinging the external IP was successful, but when I tried to access, I got this error:</p>
  
  <p>"Failed to connect to 104.154.87.175 port 5000: Connection refused"</p>