@Toto7 Check hardware version of your Deco M4. If it is V4, there is firmware for it that can let you configure how Deco connect to each other: https://community.tp-link.com/en/home/forum/topic/581554

@DivineJimmi Connecting two routers to two Deco Ethernet ports will not work the way you want to. Also, it is not very common configuration for home network to have two routers. Do you have two...

@my2108 TP-Link offers two WiFi mesh systems: OneMesh and Deco. They are not compatible. Powerline adapter TL-WPA8631P description says "OneMeshTM - Works with your OneMeshTM router." You can use...

@Tilloubill You can safely power off and on Deco unit, it will not lose its settings.

@MasonJo You did not tell that, so I am clarifying: have you just reconnected Ethernet cable, or did you powered off/on Deco, too? To avoid issues, the right process should be: power off all Deco,...

@my2108 In case i need to add additional node into the mesh network, I assume I can add any variant of Deco series..am I right? Any variant of Deco series can run with M9 Plus, but if you want Deco...