May I know what's the model number of your client device which is running the speed test?

The actual download speed (speed on the application layer) is always decided by the link speed of a client. It's usually half of the link speed or lower due to the wireless environment. When you get a low speed on the client, it's recommended to check the link speed at first. You can search online for how to as different clients may have different methods.

The link speed is also related to the distance and obstacles. Kindly have a check if you get a lower speed result.

I make Test with SpeedTest by Ookla , I want to boost my wifi , I can get 2 mb on test by Ookla , and after couple of min i can get 200 mb

Please explain what you mean by "The actual download speed (speed on the application layer) is always decided by the link speed of a client. It's usually half of the link speed or lower due to the wireless environment."

For you, (who or what) is "the client"?

Why would it be half in any case?

In my case, I have 3 Deco M5's.  My router speed from my cable provider is 55mbps down.  

My Deco app's speedtest says 55mbps.  

My laptops show 28 Mbps (or worse).  They are new(er) machines and their network adapters are updated with the most recent drivers.

Why do they receive half the rate of what is being transmitted?