Yes, you can connect the AP from one site to the controller on another site. Via VPN, Internet or MPLS link. However, below are some points which we need to ensure for the successful connectivity: 1. AP should be able to reach the controller IP. With les packet drops. 2. Controller should either be on the public Natted IP if the AP is reaching the controller via Internet. 3. Necessary ports to be allowed between the AP and controller. 4. AP should be supported on the controller software version.