According to https://www.tp-link.com/us/support/faq/1794/ , mixed backhaul (wired + wireless) is not supported.
>> Note: The Wi-Fi backhaul and Ethernet backhaul won’t work at the same time. When two Deco units are connected via an Ethernet cable, the Ethernet backhaul will take effect and Wi-Fi backhaul will be disconnected.
I don't understand why it cannot be supported, especially for AP mode.
According to this FAQ: https://www.tp-link.com/us/support/faq/2399/ , two AP mode units can be connected via Ethernet to the main router, establishing an Ethernet backhaul. Can I add another AP mode unit, not connected via Ethernet? What would happen if I do that?
I plan to mainly use Ethernet backhaul connections for the rooms where Ethernet ports are already available, and add wireless backhaul supported AP-mode unit for hallway (where ethernet is not reachable from the main router)
I am waiting for my order of 3-units.