Its not recommended to do VLAN changes for guest as there are issues with java active X applets and you have no control of guest devices.
There is no supplicant like dot1x to control the IP change
If you must change IP addresses, then the recommendation would be to do either of the following:
· Don’t use the applets
· Setup a low DHCP lease time for the initial VLAN so when the user moves its updates quickly
· Have the user login with CWA and then Register the endpoints by redirecting to a hotspot portal that will disconnect them after registration and cause a new connection on the new VLAN coming through
· Use dot1x for the guests by pre-registration or have them register for an account (make sure you use an account that’s activated immediately (from first login or make sure to check the bypass guest portal in the guest type)