@Benjamin19838 Is the exact model Archer C1200? You may check it by verifying it on the device's bottom label. TP-Link currently only has some models that support EasyMesh, which allows you to...

@Tanque Have you ever changed the QoS settings on the AX55? Make sure it is disabled as per this FAQ. You can also try resetting the AX55 to factory defaults, just connect it to the cable modem and...

@Dominik1 Maybe you can install the early released version first on the Archer C80, then monitor the connectivity again. Early Release Firmware Adding EasyMesh Ethernet Backhaul for Archer C80/C64/A8

@luke3 I guess Archer C9 will not get updated firmware for WPA3 as per the WPA3 Compatibility List.

@RufusMcDufus You are correct. It seems the only difference between the AX72 Pro and AX72 is the 2.5 Gigabit WAN/LAN Port as per the comparison:...

@obyvacka20 It seems the only option would be setting a static IP address on the AX20. You can check this thread, and that does work.