One for the community
(Apologies if its the wrong group).
We've had a few instances in the past few weeks where a customers ExtremeGuest Essentials CWP has stopped working and the fix has been the format of the SSID.
If the SSID has a character at the start such as an underscore then the CWP doesn't like this format and will not allow the CWP to display.
We have deployed SSID's with an underscore because of the limited number of SSID's a mobile device can see and if your in a managed services building with multiple tenancies and your company happens to start with a 'W' then you will not be able to see the SSID to connect so by using "_W" instead then your devices are more likely to see the SSID.
Anyway... hope that helps someone.