We noticed during recent testing that FortiClient 7.0.2 has an issue with Firefox, specifically any Google services such as Google Search and GMail.
While web-filtering was enabled on the client an initial access to Google would work in Firefox, however after a minute or so nothing would happen when trying to refresh the browser session.
The root cause appears to be related to 0RTT (Zero Round Trip Time) and only affects Firefox but not other browsers. Fortinet has tracked this as bug ID 766869.
The issue is resolved in FortiClient 7.0.3 and a workaround is to disable 0RTT in Firefox using the following procedure:
Firefox browser window:
- about:config
- Search for security.tls.enable_0rtt_data
- set the value to false