I got it working using another pc. Firmware update is ok. Feeling stupid but thanks.

@Somnus i tried that but non of thema work. Ik haven't tried a reset yet because of the hassle.

I'm unable to update the firmware of my EAP265 HD access point. I don't use the controller software, it is a standalone access point. Current verion 1.1.0 Build 20200619 Rel. 58617(4555), version I...