Can they not be exclusive systems? the Asus gives my house wifi and is my main router (every device besides my pc will connect to) and the R3 is a lan only to my pc. Through scouring the web I thought this was possible. I would set my R3 in the DMZ of my asus and they would be exclusive systems since my R3 would feed and only be needed for one device.
Another option I saw through scouring the web was that the R3 would be my main router at the 4x Asus would be put into AP mode and basically be fancy wifi extenders. This on paper is fine but I also read that in doing each client will control which node it connects to and not the AiMesh wifi system. So if I walk from one side of my house to the other there could be some lag time (on my phone, for instance) in switching between nodes where as it is currently very fluid using the AiMesh.