I set up a two deco x75 mesh system in my house month ago and I want to add one additional x75 to my bedroom.  When I added it to my system and plug into an Ethernet port in my bedroom (which I confirmed worked by plugging into a laptop), the new deco says it's connecting to the main system via WiFi and not Ethernet (like my second deco shows in the app). How do I get my third to recognize the Ethernet and not use WiFi?