The TP-Link Deco M5, which I bought and started to use yesterday, should be sorry to say that it was a big disappointment for me.
I installed the devices in AP mode. I have a modem in the entrance of my house and CAT6 cables from this modem to every room. The house is L shaped and there are 5 rooms in total. I installed the Deco M5 in the second and fourth rooms after the entrance and made the installation.

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FiberNet —>Router (H267A)————DecoM5(mainDeco) [AP mode]
                                       |————-—DecoM5-1 (slave) [AP mode]

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Problems I had;
1- If I come to the bottom of one of the devices and turn on my internet, 5Ghz connection is established. But if I go next to the other device (which is 2 side rooms) it still continues to connect with the first device. The connection speed sometimes drops to 2.4, but the speed is very low, as it does not connect to the device at the bottom. (very often)
The only reason for giving this much money to this device is that it doesn't automatically choose the most suitable (2.4GHz / 5GHz) frequency to the nearest station.
2- When I move away from the side of the device, after a certain distance, it starts to not be able to draw 5Ghz, it switches to 2.4 GHz connection. However, when it comes back to the device, it does not return to 5GHz connection. To do this, I had to turn the wifi off and on. (Not always but often)
I waited 2 minutes for both conditions. I could not stand any more, I turned the wifi off and on. I think 2 minutes is a very, very long time.

I bought this device at home for media stream, backup and file transfer. Considering that my internet connection speed is 100Mbps, this connection may seem partially sufficient, but what I need is a home network that will provide gigabit connection.. If my goal was just to connect to the internet, I would buy a much cheaper AP. Unfortunately, I was not able to use the mesh technology as described.
Unfortunately, I did not like the product under all these conditions.
Also, I think the wifi signal strength is weak. The current modem in my house broadcasts better. (H267 A)

1.4.4 Built 20200221 Rel.65392