How to configure SSID Private and public WAC500

Hello,

I would like to know if it's possible with the WAC 500 in standalone mode to make 2 SSID.
Exemple :
Private for all users in the company 192.168.x.x

Public for the external users 172.16.x.x

The step to create the two SSID is quite easy but the two SSID get the same DHCP…
I try to change the ID VLAN on the Public SSID but i don't know where to manage other VLAN in WAC 500 ( or if it's possible? )

Thanks for you answer,
Damien