@Andrewdj 

Based on Deco map, you have M5 and also some other Deco model: is it M4?

Also, do you have ISP router in front of Main Deco or just modem?

  @Alexandre. 
its deco E4

All the deco connected through switch router gigabyte

and also the isp modem connected to the main deco

im wondering should i connect the isp modem to main deco or to the switch hub?

  @Andrewdj 

Please give me ISP modem brand and model number. That will help me to figure what you have. 

Connecting switch to ISP modem and all Deco to switch will substantially offload Main Deco, but your ISP modem must provide router functionality and some configuration must be done on Deco mesh.

That's why I need to find what ISP modem you have. 

  @Alexandre. 
it is standart from the isp

i checked the back of the modem 

huawei echolife EG8145V5

GPON Terminal

  @Alexandre. 
I tried slot 4 originally and also slot 3 and 2 all works fine. the internet speed test come with same result

  @Andrewdj 

That means your ISP modem/router is configured as router. That functionality can be offloaded from Main Deco.

Here are two steps you can do to improve Deco mesh performance:

1. Configure Deco mesh to run in Access Point mode.

No network layout changes are necessary for that, it should be simple configuration change through Deco app. See Switching a Deco to Access Point (AP) Mode

Most devices on your home network should take that change seamlessly. If any loses Internet access, give it 5 minutes and then reboot it. Should be enough.

After everything settled down, you can proceed with next step.

2. Change network layout to remove Main Deco from traffic between switch and ISP modem.

With Deco mesh running in Access Point mode, you don't need Main Deco handling all wired traffic. You can redo your network layout to become as following:

---------------

These are steps I recommend for anyone who wants to improve performance of their Deco mesh. If these are not enough, for example you want faster WiFi than what M5 and E4 can deliver, I can help with choosing Deco model(s) to replace them. Still, I will recommend to keep both Access Mode and network layout with network switch connected directly to ISP modem.

  @Alexandre. 
i did step 1 and step 2

then how do i change/remove the selection of main deco in the apps?

Andrewdj wrote

  @Alexandre. 
i did step 1 and step 2

then how do i change/remove the selection of main deco in the apps?

  @Andrewdj 

You now have Deco mesh that should work better than before, Main Deco M5 should be colder on touch.

Your question, I am not sure I understand it. What do you try to accomplish? Do you have error message in Deco app about Main Deco?

  @Andrewdj i had a similar query here

https://community.tp-link.com/en/home/forum/topic/705150

Unfortunately it seemed hard to come to a concrete answer. What I will say is in terms of range, don't expect big differences between Decos. Some "better" models are actually even worse than the cheaper ones. I think the X10 was slightly better than my M5, but I don't know if my X10 was faulty or what but it was just slow to use the app with and slow to reboot. 

I'm not sure between the X20/X50 and X60. When I look at the forum, it seems like the X50 has the best software support and features. The X60 is a bit behind, don't know on the X20. The X10 I can't complain about but it doesn't feel like a big improvement from my M5 other than WiFi 6.

I think if your devices are all currently fine with WiFi you would find the same regardless of which Deco you upgraded to, the differences aren't that big. You'd only gain WiFi 6 support and it's up to you if that's worth it. Some of the features in the X series also aren't even available unless all your Decos in the network are the same. I can't enable Mu-Mimo or OFDMA for example even when my X10 is the main because there are M5's on my network. 

Also your M5 comes with Homecare which gives you monthly reports and parental controls for free. If you upgrade to the X series and replace your main, many of them use Homeshield where you will have to pay a subscription for the same features.