WiFi with Disclaimer only shows Authentication page (username/password)

Hi,

We have a series of 60E fortigates with FortiAP's. The SSID's are configured for WPA2 Personal with Captive Portal and the Portal Type is set to Disclaimer Only.

But, whenever a user connects to the SSID, the fortigate is presenting the user with an Authentication Page (username/password) instead of just the disclaimer.

Does anybody know what causes this?

The vap is configured like:

edit "Corporate-Guests"         set vdom "root"         set ssid "Corporate-Guests"         set security wpa2-only-personal+captive-portal         set portal-message-override-group "Guest-Wifi"         set portal-type disclaimer         set security-exempt-list "Guests-exempt-list"         set intra-vap-privacy enable         set passphrase ENC XYZ next

Running FortiOS 5.6.3

Regards,

Erik