Description
This article describes the cause of Multiple 'HTTP' redirections when local authentication is enabled.
The user will face an auth loop issue if the user's machine is behind a router and after multiple tries user might be able to load the websites or the user will keep getting the auth page.
From version 5.6.4 and above, 'auth-src-mac' option is enabled in user settings by default.
Solution
This issue usually occurs when the captive portal authentication is enabled. By default, FortiGate will also check on the mac address of the client trying to authenticate and if the client is behind a router before reaching the firewall we will see the loop behavior.
This error could also be due to DNS resolution as well.
The commands to disable 'auth-src-mac' were added from the 6.0.2 version to resolve the issue.
config user setting
set auth-src-mac disable
end
