I just installed my set of Deco M4's. I just returned my XE75 set as my older laptop could not connect to it using Wifi 6 protocols.

The router of my ISP is acting as the main router in my setup. I have set the Deco to acces point mode.

The main deco is directly connected by a network cable to one of the ports of the router of the ISP.

On the second floor I have an old ASUS AR-AC87U router, also in acces point mode. The WAN port of this router is connected directly to another port on the router of the ISP by a network cable. This has always worked fine.

I have connected the second Deco with a network cable to one of the ports of this ASUS router. In the demo app, the connection shows as wired and this works fine.

But when I connect the 3th deco with a network cable to another port the ASUS router the problems begin. At first also this connection shows as wired in the deco app, but then app reports that the internet connection on the entire set it lost. And indeed the internet connection on my devices drops. The only way to resolve this is by disconnection the netwerk cable to the third deco and after a few minutes the system restores itself. Then the third deco is wireless connected to the second one.

Even when using that same network cable, but now plugging it into the second deco directly instead of the ASUS router, the problem comes back again.

What is wrong in this setup? Why? And how can I cannot the third deco wired? The problem is not in the wiring, it is already there for some years and did not cause any problems.

Thanks for your help!

Gert