Do you access this device via an open HTTP connection or via a secure HTTPS connection? <p>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> <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.<br> You can press the ESC key to close a doorhanger with a warning message in the name and password field.</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> </ul> <p>More:</p> <ul> <li>https://blog.mozilla.org/tanvi/2016/01/28/no-more-passwords-over-http-please/</li> <li>https://blog.mozilla.org/security/2017/01/20/communicating-the-dangers-of-non-secure-http/</li> </ul>