Not a solution, but some related information for you. . .
I' m also using FSAE with edirectory. The FSAE agent tends to give off errors on the server. Don' t know why. Have not been able to solve. Others have reported the same issue (search forums for fsae), but seems to continue to function OK.
I don' t use non-authenticated guest access, so have not seen the issue you' ve mentioned. Guest users need a guest password for a web login on my network.
What firmware and FSAE version are you using?
Once authenticated, the Fortigate needs to periodically re-authenticate the user if it hasn' t seen any traffic from that user. If that re-authentication fails, my guess is that it reverts security to Guest (unauthenticated).
The trick is to find out why the re-authentication is failing.
My advice would be to change your authentication timeout temporarily to something like 2 hours to see if that has any affect. If so, then at least you' ll know you' re on the right trail.
The setting is in User|Options.
If it' s any help, you can also use the CLI to set specific timeouts for different groups. My guest logins reauthenticate every 15 minutes. But my FSAE logins are much longer -- typically just people logging in for the day at their own desktops. No need to constantly reauthenticate those.
Bill
Bill
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Fortigate 600C 5.0.12, 111C 5.0.2
Logstash 1.4.1