Cann't connect to wAP-AC

I have a wAP-AC, which was successfully configured last year, but has now been permanently installed. Now I am unable to connect to the device via Ethernet. I have already performed a reset several times. I am using Linux Mint 20.3 and autoconnect does not connect. Does anyone know a solution?

On resetting to defaults the wAP-AC will have an open wireless network. Have you tried to connect to that? It might have a firewall configured on the ethernet port.

I have performed a reset and can see the wireless network, but it is protected. Could the reset have been unsuccessful?

Now on a Windows laptop with WinBox tried, but also without result.

ipconfig:
Ethernet adapter Ethernet:

Connection-specific DNS Suffix . :
Link-local IPv6 Address . . . . . : fe80::3593:ae46:ea58:ab8c%19
IPv4 Address. . . . . . . . . . . : 192.168.88.1
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :

It all seemed to be resolved, the reset apparently went wrong. The old ip address and password were still active. But now I have another problem. The POE seems to be broken. The power light is off… :frowning: