@David-TP  The layout is around ISP---Router---Main deco M5---Deco M5---Deco M5 they are roughly 5 meters apart from each other I'm not expecting full speed at the end but i was hoping for something better than 200 because i done a speed test on the app it said 870 but yet i still only get 200 i would even be happy with 500-600 from them

  @JasonGreer 

>The layout is around ISP---Router---Main deco M5---Deco M5---Deco M5

I am assuming Satellite Decos are wirelessly connected, not through Ethernet cable.

On Main Deco M5, you should be able to get up to 500Mbps with WiFi 5. This is the best I ever got with M5, in many, many speed tests.

Each Deco hop will cut that speed by half. On first Satellite Deco you'll see up to 250Mbps. On second and last Satellite Deco you'll see at most 150Mbps. If you see more there, it may be because second Satellite is connected to Main, or because it delivers superior performance.

It is not Deco issue, but technology limitaitons. Google for "Why do Wi-Fi range extenders cut bandwidth by half"

As for speed test in app, it tests Ethernet link from Main Deco to Internet and should deliver closer to what ISP sells you in Internet package. This is wired speed, not wireless.