I'm really impressed with the performance of Dlink products
My main router = Netgear Nighthawk R7800 X4s
1st Room = D-Link DAP-1860 & D-Link DIR-882 in the same room Hard wired connection from 1860.
Pairing my Netgear R7800 to the Extender & then to DIR-882 Router I'm able to achieve 530 mbps of speed, which is basically maxing out my broadband speed in my 2nd room.
I tested the speed using my LG G7+ & a Samsung S8+, both of them are able to get max speed as if being in the Hall close to the router (530 mbps).
Also this is happening through 3-4 Concrete Walls.