I would like to suggest a configuration to disconnect a non authenticated client in a Hotspot Portal after a certain time in pending status. 
Exemple:

1 - client connects in SSID (with or without security), authenticating with HotSpot portal (Voucher or Form Authentication or whatever);
2 - after 3 minutes without Portal athentication Login, client is automatically disconnected;

3 - client connects again, and timeout Portal authentication another time;

4 - After 3 times consecutives authentication timeouts, the client automatically gets 24 hour Block.

All times could be customized.

I suggest this beacause some smartphone try to connect automaticaly when finds a WiFi network without security password. 

Thank you,

Dimitri Toledo