@TP-Link Here is my topology. I am not sure how to check for the deco strenght. The ones in the second floor are maybe 30ft apart. I am assuming my phone is connected to the 5Ghz channel when testing...

@andrewl923 I have also experience inconsistent internet speeds. Range is also horrible after updating to Deco M9 Plus(US)_V2_1.5.1_210126 firmare. I have 800mps internet, wired to deco does get good...