I don't think the archer-ax23-v1 OpenWRT image is going to work on this device. It looks like AX1800 v5.6 uses the same firmware as AX23 v2, which is called out as being a different SoC than the supported AX23 v1 on the AX23 device page: [OpenWrt Wiki] TP-Link Archer AX23.
AX1800 USW v4.6 will work with that image, though: TP-Link AX1800(USW) Ver:4.6 - For Developers - OpenWrt Forum.
Looks like there was a forum thread attempting to add support for AX23 v2: Adding OpenWrt Support for TP-Link Archer AX23v2 - For Developers - OpenWrt Forum. The hardware picture on that one looks similar to what is posted here.