My wife and I moved from a standard apartment unit to a basement apartment that spans nearly the entire basement of that same building. The Archer BE900 is more than capable of getting a signal to the whole square footage of our unit, but we have multiple, thick, concrete walls which separate our office space from our living space. The signal cannot transmit through those walls, so I purchased a second BE900 to act as a satellite device for our main router. 
We are using an fiber ISP and our main router is hooked up via Ethernet. As I was looking into the units to purchase I noticed the BE900 has a SFP+ Fiber/RJ45 combo port, and doing surface level research, found I can utilize the SFP+ Fiber/RJ45 combo port to hardwire both routers together over a fiber line. So I found a fiber wire, set the whole system up, and found the setup only works if both routers are in AP mode. Apparently the technology is available, but we are waiting on a firmware update to enable the use of a hardwired AIMesh system--particularly one that allows the utilization of the SFP+ Fiber/RJ45 combo port when you have a main router and a satellite router. 
This thread is to request that feature be made available ASAP, especially because my network has IoT devices spread through the unit, and the other feature currently unavailable is the AIMesh extension of an IoT network (someone already has a separate thread for that and is relatively simple to find via a search of TP Link not extending IoT Network on EasyMesh).