Is the Ap having default Ip and trying to discover the ZD? There has to be connectivity in between the AP and ZD in the first place for it to join the ZD. Please try pinging ZD's Ip from AP and if you cannot ping the ZD then that needs to be looked at first.
apologies for the slow response. I have 2 different setups and was only able to get one fixed.
in scenario 1 the ZD 1100 has static ip address for the APs
I was able to give the AP a static IP address that matched what was on the ZD and it reconnected.
in Scenario 2 the ZD 3000 is an environment with a dhcp server and communicates with the APs via specific Vlan.
the AP auto-discovery does not appear to work. Giving it a static address and the same subnet mask as the ZD does not work. Resetting to factory default then manually setting the director ip does not work.