@relayman I would like to interject into this conversation with a suggestion. Would you please swap Main Deco and Satellite Deco, so that Main Deco is on the left side of the picture. For Deco mesh...

@NetanelC I may be able to suggest workaround, which is to rearrange your network layout, but I need more info from you before I can do that. You must have more than one Deco X20. If you do have more...

@NetanelC On your PC, check what Ethernet speed it negotiated with Deco X20 it is wired to. See How to check the associated/link speed on a wired client If PC negotiated 100Mbps, you'll need to focus...

@HJO Using UTP cable is called Ethernet backhaul in TP-Link Deco terminology. I use that for my Deco M5s and it works just fine. See this FAQ: General questions about Ethernet Backhaul feature on...

@richiee Main Deco must be connected by Ethernet cable. You can't have Main Deco wirelessly connected to the router.

@Jeff1976 The official TP-Link answer will be "any other Deco model is compatible," but in your specific case with WiFi5 Deco mesh I would recommend to consider the following: Deco M5 Deco M4R Deco...