title: Compute Engine HTTP Load Balancing 502 error
body: <p>We're having significant issues with our http load balancer from certain IPs only.</p>
  
  <p>I've seen a few other posts here about this. We've made sure the firewall is ok, I've even deleted and recreated the forwarding rules. Which is blasted annoying since the IP changes.</p>
  
  <p>Still no joy. The problem <strong>only affects certain IP addresses</strong> - and if I post the same data to the IP of one of the servers, I have no problem.</p>
  
  <pre><code>&lt;html&gt;&lt;head&gt;
  &lt;meta http-equiv="content-type" content="text/html;charset=utf-8"&gt;
  &lt;title&gt;502 Server Error&lt;/title&gt;
  &lt;/head&gt;
  &lt;body text=#000000 bgcolor=#ffffff&gt;
  &lt;h1&gt;Error: Server Error&lt;/h1&gt;
  &lt;h2&gt;The server encountered a temporary error and could not complete your request.&lt;p&gt;Please try again in 30 seconds.&lt;/h2&gt;
  &lt;h2&gt;&lt;/h2&gt;
  &lt;/body&gt;&lt;/html&gt;
  </code></pre>
  
  <p>EDIT</p>
  
  <p>We use cloudflare - usually this is actually disabled for this host however, I have just re-enabled it and now traffic is accepted again. Presumably since the traffic originates from a CF ip.</p>