Hi Prahlad,
Refer below steps
1- If there is any firewall between ZD-AP then make sure all required ports are open. Also check if you are able to ping ZD from AP CLI or vice-versa.
2- What is the ZD version you upgraded to?
3- Try SSH into the AP, factory reset it, delete it from ZD.
set factory
reboot
4- now try manually point it to ZD.
set director ip
reboot
Regards,
Syamantak Omer
Syamantak Omer | Community moderator | Staff TSE | CWNA | CCNA | RASZA | RICXI | Follow me at https://linkedin.com/in/syamantak-omer-5949b6124