Currently I have 3 x60 at my house, one for each floor.

2 are connected with Ethernet cable and one on the middle floor wirelessly.

it is working fine, but I wanted to add more coverage on the ground floor for the yard and office.

I bought two more deco x20, and when I add them successfully to the network, the other decos disconnect, only the main deco stays connected, and even though the new x20 sometimes has a green light it is either not showing connected, or not able to provide connectivity. And later flashed with red light and also disconnects.

I tried network optimization, tried to reset both and re add them, tried to add only one of them, nothing helped.

The minute I disconnect the newly added x20, everything is back to normal and working great.

Both new x20 are connected with Ethernet cable.