SSL_ERROR_BAD_CERT_DOMAIN will not record my website Exception

Situation: I am an automation tester working inside a firewall on a server without a valid certificate. I am working on Windows 10 and Windows 7 with Firefox 59.0.2. Chrome and IE allow me access to this website but Firefox refuses. Requirement: I need to make a permanent exception for my test server in Firefox. Problem: When any https://services-sandbox.hopewiser.com pages are opened the "Your connection is not secure" page is displayed and though the Add Exception button allows access to the website at that time, the website is not recorded so can not be used by my Selenium scripts. The Selenium scripts crash as soon as the "Your connection is not secure" page is displayed so I can't click the Advanced and Add Exception button on the screen. On the Add Security Exception I always tick the "Permanently store this exception" before I press the "Confirm Security Exception" button. I have tried doing these steps in "Private mode" and "Restart with Add-ons Disabled" and many other steps mentioned on the web but to no avail. NB. This page mSupport page would not allow me to add my .png screenshots.