@Handpol 

You do not need to use fastest Deco as Main Deco when Deco mesh runs in Access Point mode and everything is connected by the Ethernet. 

This TP-Link recommendation is mainly for Deco Router mode, where Main Deco does heavy lifting of content filtering, antivirus, bandwidth management - for all traffic going to/from Internet. These all features are disabled in AP mode, thus not taxing Main Deco CPU.

Just make sure you do not have network layout like that, where all traffic goes through Main Deco:

Instead, this one should work better for your Deco mesh:

If you build you home network that way, traffic from devices connected to each Deco will go directly to Modem/Router, not through Main Deco. Also, with this setup Deco mesh will use undocumented resiliency feature: if Main Deco fails, one of the wired Satellites will silently assume Main Deco role and devices connected to Decos that still online will continue to have Internet access.

@Alexandre. 

thanks for the information (specially the one with hooking up the X50's on the switch) but would it work in a meshed enviroment this way? 

If i have a look at the FAQ of TP-link itself they claim exactly the opposite. 

What I'm trying to achieve is running a router(AX11000) => switch(TL-SG1024) => X50's with UTP (just as the picture below)

but the FAQ has this one:

Link: https://www.tp-link.com/no/support/faq/1794/

  @karakan08 

You can have that topology if you run Deco mesh in Access Point mode. Switching a Deco to Access Point (AP) Mode