@Alexandre. With the deco in Access Point mode I can get 310 Mbps. repeated the test with the MEO router and got 440 Mbps

  @diogo_ 

An improvement with Main Deco, but still below expectations.

Keep Deco mesh in Access Point mode and do two more changes:

1. Enable only 5GHz for Main Network:

2. Power off Satellite Deco, keep only Main Deco running.

Run speed tests again in that setup. Make sure that device you run speed tests on is not more than 1-2 meters (3-6 feet) from Main Deco, in direct view of it.

If that can't bring better results, check what is associated/link speed on your wireless device that you use to run speed tests, when it is connected to Main Deco: How to check the associated/link speed on a wireless client

Then, check it again with same device connected to MEO Router WiFi. Let me know what you have with both.

Regardless of results, you can undo all changes I asked you to do, after that point.

  @Alexandre. 

I did the test but it still had the same results...


Results of the test:
only one DECO M4 in Access Point mode and with enable 5GHz wifi only:

Download speed 245Mbps

From the MEO router with wifi auto 2.4 and 5Ghz 
Download speed 511Mbps

Do you think this problem may be a network IP configuration?
I have everything set to auto. Any idea on how to solve this?
In this moment, I think I may have misconfigured the Decos M4.

  @diogo_ 

It is almost impossible to misconfigure Deco mesh that runs in Access Point mode.

You have tested Ethernet link and it delivers expected speed.

By switching Deco mesh to Access Point mode all bandwidth throttling and content filtering configuration settings that may have been misconfigured were disabled. In AP mode, Deco mesh just passes WiFi traffic to MEO router and does little else.

Leaving only 5GHz made sure device that is used for speed test is connected to Deco mesh by WiFi5, which is 5GHz. With dual-band, TP-Link band steering algorithm prefers 2.4GHz. You have disabled that by explicitly configuring Deco mesh to run on 5GHz only. WiFi5 is the fastest for Deco M4.

By turning off Satellite Deco you made Main Deco into standalone WiFi router. With Satellite offline, Main Deco no longer uses any resources to manage WiFi mesh.

By this point, what you have is standalone TP-Link WiFi router (Main Deco) that broadcasts WiFi5 only and has all its bandwidth throttling and content filtering settings disabled. As a WiFi router, it should deliver similar WiFi speeds as MEO Router.

Why it does not, I can't explain. The difference is dramatic. If it were 20% one or other way it could be explained, but I have no explanation for 2 times difference.

At this point, my recommendation would be return Deco mesh hardware to retailer if you still can and try some other brand of WiFi mesh. If your ISP provides range extenders or WiFi pods compatible with MEO Router and capable of creating WiFi mesh with it, you should try those first.