@Heymarcoh Well, then what's left is crazy creative stuff. Promote that strange Satellite Deco to Main Deco and see what happens: Changing the Main Unit for your Mesh Network

@Heymarcoh This is unusual case, what I can suggest is basic troubleshooting steps. 1. Do you have anything connected by Ethernet to that E4, such as PC, Smart TV, etc.? If yes, disconnect them and...

@stellaren If all your Deco M4 are with hardware version V4, there is beta firmware which will let you configure how Deco should connect to each other:...

@PCV For Deco M5, check the following TP-Link FAQ: How to select a preferred signal source on the Deco App

@Heymarcoh From the screenshot you provided it appears your Office Deco is connected by Ethernet cable. Is it not so? When Satellite Deco connected by Ethernet cable, it won't report signal source...

@DrillNBass Also, if you are considering buying Deco X50, it makes sense to add it as a Satellite and after that promote it to Main Deco. By doing that, you'll preserve all current Deco mesh...