@pedrot 

As much as I like my Deco mesh with M9 Plus, in your specific case you may find issues by coupling Deco and 4G router. I can see two potential problems:

1. This HUAWEI router has single LAN/WAN autosensing Ethernet port. Deco Ethernet ports are also LAN/WAN autosensing. It is possible that HUAWEI and Deco may not be able to figure if Ethernet connection between them is LAN or WAN, and it won't work.

2. Deco runs constant Internet health checks. If your 4G connection is too slow or has high packet loss, Deco may assume Internet is down even if you manage to get Internet traffic on devices connected to HUAWEI WiFi. If Deco assumes Internet is down, it won't pass Internet traffic.

If you still want to try Deco mesh, make sure you buy it from the place with at least 30 days return policy.

Also, while I do prefer M9 Plus to any other WiFi5 Deco, TP-Link does not sell single Deco M9 Plus units. They are sold in 2-unit and 3-unit sets. Which means, if you buy 3-unit set and decide to add one more M9 Plus later, you won't be able to buy single unit.

I don't know why TP-Link decided to do that, because these 2-unit and 3-unit sets are not preconfigured in any way. You can buy multiple sets and add them to Deco mesh, but you won't be able to "buy 3 now and add one more later." Which means, you either have to figure how many you need before you buy them, or assume you may have to pay for additional 2-unit set even if you only need to add single M9 Plus.

Wow. :) Thank you so much, Alexandre for your complete reply.

Unfortunately, I will have to wait for the cable or optical fiber to reach my area to be able to use the Deco M9 plus Mesh.

By the way, at that time I will make a contract with the internet and television operator company. My question is, will it be enough to place the Deco M9 plus with the fibre or cable router provided by the internet operator and it will work fine?

  @pedrot 

If you are asking will Deco M9 Plus work with cable or fiber Internet, the answer is yes. I have Deco M9 Plus in my house, connected to ISP cable modem/router, for over a year.