@TP-Link Ok, so let me get this straight. Your suggestion is for me to figure out which devices may have this compatibility problem and replace them all, so they become compatible with your device? That's an amazing fix! Will TP-LINK pay for all the new devices? 

@AmirBeh 

Someone sold you mobile device that you have found can't properly work with WiFi mesh. You should contact that someone for an explanation, fix or refund.

On my 3 nodes Deco mesh network, when mobile device that is near my Deco Node 1 wants to connect to WiFi it will see this:

If mobile device in this location fails to connect to Deco Node 1, with the best WiFi signal quality, but connects to Deco Node 2 or 3 instead, that is device problem.

FYI: this screen comes from WiFi Analyzer app installed on smartphone. 

@Alexandre. No body sold it to me, I bought it off Amazon. 

@AmirBeh 

If you bought mobile device on Amazon, and that device can't properly work with Deco mesh, because it fails to connect to the nearest Deco - leave critical feedback on Amazon web site, contact mobile device manufacturer through Amazon or directly through their Web site.

Ask device manufacturer for explanation why their device does not understand WiFi mesh, such as Deco mesh, and ask device manufacturer for fix or rebate.

Also, can you tell what is that device that does not understand how to roam on WiFi mesh to the Deco node with the strongest signal, what is its brand name and model? 

@Alexandre. Dude what are you talking about? Do you work for TP-Link? I bought the Decos from Amazon. I have laptops, desktops, mobile phones, printers, iPads, Macbooks all around the house connecting and half the wireless devices have this issue and they are max 3 years old. This product definitely is the issue and they should have added these features PERIOD. My PS5 has the same issue to the point I had to hard wire it in. And the main deco is literally 2.5 meters away and it's still connecting to Deco on the 2nd floor. 

@AmirBeh 

I do not work for TP-Link. I am Deco mesh owner for about 4 months now. This is my first WiFi mesh.

There are three Decos running in my house, two M9 and one M5. I have smartphones, tablets, desktops, network printer, android smart TV, Roku (for different, not so smart, TV), android set-top box, Kasa smart plugs - they don't have issues with Deco WiFi.

When I turn off/on WiFi on mobile device, it connects to the nearest Deco. When I walk around house with smartphone, it roams to the nearest Deco, before signal from one it was connected to gets weak. I have stubborn Surface Pro 4 tablet that does not roam aggressively, I had to tweak settings in that Windows tablet to improve its WiFi roaming capabilities. 

TP-Link Support may be trying to be polite with you, because they do not want to upset valuable customer. I do not have that concern, so I can tell you the truth: this is not TP-Link Deco mesh problem.

WiFi mesh, not ony from Deco, has marketing problem. It is more complex networking gear than just a single WiFi router. What you will get from deploying WiFi mesh at your house depends on your understanding of WiFi mesh principles, limitations, mesh nodes best deployment practices, and what mobile devices are running on your home network. Internet research and some self-learning may be required.

That is not what people are told when they buy into WiFi mesh: they are promised "seamless WiFi coverage" and "automatically chooses the best connection for your device," implying that it "just works." 

If return window for your M5s is still open on Amazon, I would recommend you return Decos.