Remove the certificate warnings by trusing the CA certificate.
Download the cert - http://gateway.ed/CA.crt
You can install it, or install it into the group policy (trusted CA certs) on your AD server
This should work for IE and Chrome.
Add the CA Cert here in your group policy: GPO Path - Computer Policies --> Windows Settings --> Security Settings --> Public Key Policies --> Trusted Root Certificate Authorities
Try setting the option in firefox to make it automatically import trusted system certs.
Make 2 files on a share w read permissions for Domain Computers (e.g. sysvol?) Add them to the AD files rule at "Computer Configuration -> Preferences -> Windows Settings -> Files"
pref("general.config.obscure_value", 0); pref("general.config.filename", "umbrella.cfg");
lockPref("security.enterprise_roots.enabled", true);