Bridging wlan to ether with hap ac²

I am trying to use a hap ac² to connect ethernet only devices to a wireless router in another room. As far as I understand CPE mode should do this.

Procedure I tried:

After I do this I can no longer access webfig at http://192.168.88.1/ or connect to the device via winbox. Not sure what is happening. When I check with wireshark I can see SYN packets going out on the Ethernet interface but nothing coming back. Ping still works though.

Any ideas why this is happening? Is there some way I can get it to not happen?

I don’t have experience with various quickset modes … however I assume that CPE is intended for WISP-provided device and is thus configured so that management access is possible through wireless interface (WAN) rather than through LAN interfaces. Either way it will probably contain a firewall and I’m not sure you want to have firewall between parts of your LAN.

The wireless router in the other room, which vendor is it? While WiFi standard doesn’t support transparent bridges between two wired islands, different vendors came up with their own standard extensions. Unfortunately they are not compatible, but if both wireless devices are by same vendor, then it would most probably be possible to create such a bridge. In that case both wired parts of your LAN would act as if they were connected by wire.

As mkx noted there are many traps and pitfalls via the method you want to use.
Often as well depending upon devices one loses considerable throughput.
Have you thought of perhaps using MOCA adapters or Powerline adapters to get the signal to where you want it to go?
Another option, which may be a bit pricier is do a window to window transfer through wifi where line of sight LOS can be employed.
For example pointing these two devices at each other (outside basement window to far corner of house, outside 3rd floor window).
Two of these units—> https://mikrotik.com/product/wap_60g, OR
This pair—> https://mikrotik.com/product/wireless_wire_cube

The router is some Sagecom device with custom firmware for my ISP.

I will consider this.

I can basically do what I want currently with a TP-Link TL-MR3020 if I put it in AP mode and select repeater/bridge and just disable the WiFi AP, the main downside for me here is that I need a separate switch as I want more than one device on it.

I will maybe try setup things without Quickset and see what happens. All I want is basically to have a switch which is connected to my ISP WiFi router in the other room like there was a normal cable running to it.