I've just recently made a purchase of the Deco S4 3 - Pack, placed them around the entire house, and they're literally in the next room, but get really bad speeds, I also tried connecting via the ethernet directly to my PC, and am getting under 200Mbps, I tried switched over to my old router just to check, and my old router connected via the ethernet gets 900mbps which is around the speed I am paying for. 

I don't know what's wrong with these deco's this is not what it had advertised on the box. In the same room as the Deco S4 (main). Can't even get decent speed via WiFi either. 

Am I doing something wrong or are these just commonly like this? Please help