@NoAngel Here is what I have. My Synology NAS DS220+ is wired directly to the router (it would be to Huawei EchoLife HG8045Q in your case). I run Deco mesh in AP mode, just like you. With that setup,...

@JGMH MFC J985DW printer description says it has Ethernet connectivity. Try connecting printer with Ethernet cable to one of Satellite Deco, to see if that works.

@kbs404 Also, here is how to use that feature when it appears in Deco app: How to select a preferred signal source on the Deco App

@kbs404 Deco M5 official firmware has the feature (Connection Preference) that allows to configure how Deco units connect to each other. M4 - does not. For that feature to be available in Deco app,...

@Koeke This TP-Link FAQ document should help: General questions about Ethernet Backhaul feature on your Deco

@GyanAccessFreak You can add M5s to Deco mesh that runs on X55s. Check prices for X10s, if they are available in your region and for similar to M5 price, X10s are better addition. They support WiFi6,...