@KingPing I believe this message appears when M5 negotiates 100Mbps Ethernet link instead of gigabit. Modern networking equipment is often gigabit or more, so having 100Mbps might point at Ethernet...

@KingPing It is possible TP-Link started to use new MAC address prefix, and it is unknown to that app. Google for web sites offering "MAC address vendor lookup" and try M5 MAC address through them....

@Loco9 If Deco app shows low signal for Satellite unit, you must move that unit closer to Main Deco. I am assuming you are talking about low signal from Show List screen in Deco app, such as:

@CHAACHO Can you return this 3-unit Deco X50 set? If you can, I suggest replacing it with tri-band 2-unit Deco X90 or Deco X95 set. As a tri-band it'll have separate band for backhaul. Deco X90/95 is...

@CHAACHO I see what you are trying to do. It is creative. I have a feeling that won't work, meaning you won't get double speed from third unit, but I can't find good explanation, why. You should try...

@CHAACHO You can't disable SSID broadcast on a single Deco unit, but there may be other methods available for you to convince devices that are near the third unit to connect to third unit. How far...