This is a known issue with our current Mac version (171). Firefox support should be enabled using an add-on. Please download and install the add-on from the below link: https://s3.amazonaws.com/mobicipdownloads/macosx/firefox_ssl_support_wit...
Download it in another browser, then open the file in Firefox using Cmd+O on the keyboard and install it in Firefox. Eventually, the add-on will be automatically installed on all current and new users in the system.