@Boutroul 

Hi, 

If your switches do not have some special settings, such as VLAN settings, this network diagram you described is no problem, the two Deco units will establish the Ethernet backhaul rather than the Wi-Fi backhaul.
However, when you set up the 2nd Deco, you need put it near to the main Deco.

Hi,

Thanks for your answer.

When I configure the second Deco, yes, it is next to the first one. I must configure it with WIFI connexion. When I take it in the office upstair and I plug it with RJ45, it deconnect all DECO (red light) and I lost Internet connection with all Deco.

After, I seen that only one Deco can be pluged to the box in router mode. I don't know.

Bye

@TP-Link_Deco , and concerning the Deco's where we have 3 we can connect the 3 ones, via cable in the switch to use them as Access Point distributed by the home? I mean, three separated cables RJ45 that will start from the switch separately and connecting one in each deco?

Thanks in advance for your answer.

@M.Silva 

Hi, 

Yes in Access Point mode, you can plug 3 Deco with 3 cables to the box/switch/router. But you lost NAT, parental control and Qos.

I thing I will make this config in my house et turn DHCP mode OFF (on the Deco) and use the Box DHCP server.

Bye

Tof