@AZChris Strange, indeed. If you run Deco in router mode, which is default configuration, change it to AP mode and see if it changes anything. When Deco runs in AP mode, it just provides WiFi signal...

@union Q. Do you think that if i upgrade and replace my equipment with lets say Deco M5 as main Deco or even 3 new units i will get better results? A. I do not think so. You have adequate Deco...

@union Check if your 3rd floor Deco connected to 1st floor Main Deco instead of 2nd floor Deco. This part is not clear from your post. If you find 3rd floor Deco connected to main Deco, that might...

@TECreasey First of all: do you see problems using NAS, such as it becomes unavaliable from time to time? If not, it may be possible your NAS runs in energy efficient ("green") mode, going to sleep...

@Ken12 I went with 2-pack M9 Plus. My house is two storey, about 1,800 sq. ft., plus finished basement with small home office and small workshop. My ISP provides me with 300Mbit download/20Mbit...

@growler_nyc_90 You can get TP-Link Smart plug on Amazon USA for just $9.99 (it is on sale).