After the installation of a Symantec Endpoint Protection (SEP) client or change to its assigned policy, Facebook displays an "incompatible browser" error. The Windows Update web site, and some web server based applications as well, no longer functions.
This is caused by the stealth settings in the Symantec Endpoint Protection (SEP) client firewall rule ->. Stealth mode settings (OS Fingerprint Masquerading)
Stealth mode OS fingerprint masquerading, prevents the web server and web server based applications from correctly detecting operating system and browser version, and this stops the web site or application from working properly.
To disable stealth mode by policy: