This indicates that there is a mismatch between the secret key configured on the RADIUS server and the secret key configured on the Aironet WLC dashboard or on the Meraki dashboard. This error page is displayed when
Your users click on Get Internet (if both authentication and data capture are absent),
Your users complete authentication (if data capture is absent) or
Your users submit the data capture form.
To resolve this issue, you have to enter the correct secret key on the Aironet WLC dashboard or on the Meraki dashboard.