How does this 'not secure' show? Do you get an error page or do you merely see a padlock with a strike through? Firefox shows such a padlock in two case. One is when you access the website via an open HTTP connection and the other is on a secure HTTPS page when there is mixed content present. The former is quite normal in cases where the website doesn't have a certificate installed that allows a secure connection. Firefox 51+ will mark HTTP connections with a padlock with a strike through and shows "Connection is Not Secure" if you click the Control Center 'i' button at the left end of the location/address bar. <p>Note that this message is meant as a warning that you could be vulnerable and that it shouldn't prevent (block) you from accessing the website.</p> <p>You can press the ESC key to close a doorhanger with a warning message in the name and password field.</p> <p>See also:</p> <ul> <li>https://support.mozilla.org/en-US/kb/how-do-i-tell-if-my-connection-is-secure</li> <li>https://support.mozilla.org/en-US/kb/insecure-password-warning-firefox</li> <li>https://support.mozilla.org/en-US/kb/what-does-your-connection-is-not-secure-mean</li> </ul>