@NklinK Have you enabled channel limit on site config? if so the lowest channel on EAP225-Outdoor is channel 100, if you other ap is on lower channel connection is not posible.

@Fonta EAP120 v1 is outdated, rest of your access point work with the latest controller software.

@Bonesoul look at yor PC firewall , remote network are deafult blocked. so allow ip nett from vlan1 on PC

@Harlock stable versions are not something TP-Link has yet, so it's about finding a version that is the most stable :-) I have tested the beta version and I think it works quite well. but I have...

@Harlock Have you tried this beta? https://community.tp-link.com/en/business/forum/topic/615998

@Cozz Have you tried to delete client? go to Known Clients and delete it, i guess your client connect then.