I have 3 Deco X20 devices (bought as a 3 pack).  The are all connected to an unmanaged TP Link Switch (TL-SG1024S).  The main Deco is connected to the Internet Modem directly (Ethernet).  Hardware shows as US 2.6.

1 of the remote Deco units is shown as Ethernet back haul, the other is WiFi.  As far as I can tell they are set up identically.  Any idea how I "fix" the back haul to have BOTH remote units use Ehternet?

App is version 3.5.7