Please make sure the below steps are taken care: 1. AP has the valid IP address and able to reach to Master IP address. You can login to the AP CLI (SSH) and ping the Master IP address. 2. AP has the valid Gateway IP address configured and able to ping it from the AP CLI. get ipaddr : will tell you the IP address and gateway address configured on the AP.
You can assign a static IP address on the AP with the gateway with the below command: set ipaddr wan <ipaddr> <netmask> <gateway> example : set ipaddr wan 10.128.6.219 255.255.255.0 10.128.6.1
Above are the 2 scenarios where the AP can be stuck in "Building the Unleashed Network" state. Addressing these 2 step will resolve the issue.