title: Why would varnish.service suddenly change its port? (From 80 to 6081)
body: <p>I have a WordPress site with gunicorn and varnish running on an AWS instance.</p>
  <p>This morning, the website gave a &quot;502 Bad Gateway nginx&quot; error.</p>
  <p>Upon investigation, it looks like the <code>varnish.service</code> port was:</p>
  <p><code>ExecStart=/usr/sbin/varnishd -j unix,user=vcache -F -a :6081 -T localhost:6082 -f /etc/varnish/default.vcl -S /etc/varnish/secret -s malloc,256m</code></p>
  <p>According to some notes, the port needs to be <code>80</code> and not <code>6081</code>. Changing the port to <code>80</code> fixed the nginx error.</p>
  <p>This issue seems to happen about once a year where the <code>varnish.service</code> port suddenly changes by itself and someone has to manually change the port back to <code>80</code>.</p>
  <p>So my question is - why would <code>varnish.service</code> suddenly change its port? As far as I know, there were no updates or changes anywhere.</p>