Hello Theoadon,
WiNG 5.9.1(.5) should still be able to handle AP621.
Independent model AP6521 is still supported here and controller is supposed to use the same FW package to upgrade this platform
However, take in consideration that official support of AP621 has ended wiht release of WiNG 5.9. That means, in case of any bugs found for AP621 we won't be able to escalate to engineering team.
Also, take in consideration that AP7522 will be delivered with
-WR SKU already.
You'll
need to run 5.9+ code.
Regards,
Ondrej