The answer is because of using Tunnel-Mode on your WLAN, you tell client traffic to go
to the ZoneDirector, where you need to have the VLANs they are trying to access. If you
use LBO (local break-out) the client traffic is switched onto the LAN at the AP, not sent
back to your ZD first. Does that help?
You need to understand where your WISPr authentication server is located, only at the ZD,
ie Data Center or Central Office, or from where the clients are connecting (at the AP location).