Why do devices on the network periodically lose their wifi signal?

Question

WiFi

Hello, I am writing to you with such a problem:
A local network based on RB433AH is organized. One interface is responsible for the local network (zero subnet), the second - for the wifi network (first subnet). The problem is that access to the Wifi network collected from switches and access points periodically disappears (two-story building). On devices that are connected via cable - the problem never appeared. In a completely random way, the device simply does not connect to Wi-Fi, although the network is visible. The Wi-Fi settings were rechecked several times, the rootboard (which is a dhcp server, dhcp is disabled at other points) was also subject to replacement, but the problem did not disappear.
I will try to supplement the question: up to 30-40 devices can be connected at the same time, however, the load of the central Mikrotik router does not exceed 40%.
At the moment of inoperability, the device loses all traces of the signal (an exclamation mark hangs on the network connection), although it sees Wi-Fi points, but there is no connection. Ps after some time the signal returns but the ping is very unstable 30-2000ms. To clarify, I'll say that this is a hotel, and on the floor there are 2 devices connected by cable into one wifi network "n-floor". After turning the Wi-Fi on and off, I can reconnect again, but again - until I throw it out.
I looked at the log first of all - nothing strange was noticed, it only writes that my device was turned off, as if I disconnected myself.

Answer 1

overheat? Is it by chance someone is heating dinner in the microwave? Is there a closet with a mirror in the signal path?
Have you looked at device logs? What happens in times of inoperability?

Answer 2

"In a completely random way, the device simply does not connect to Wi-Fi, although the network is visible." If the access point is restarted, is the connection restored?

Answer 3

"After turning the Wi-Fi on and off, I can reconnect again, but again - until I throw it out." on the device or when the access point is rebooted?
What is the signal level?

Answer 4

The solution to the problem seems to me in the very equipment on which the WiFi network is built.
There is such a parameter for WiFi access points / routers as sensitivity (the ability to receive a signal from a client).
Since data can be transmitted by a point and the client will not be able to send a response due to a bunch of factors (weak transmitter / sudden interference / orientation of the gadget in space, etc.).
The key sign is that the network is visible - but cannot connect.
Alternatively, there is another reason that not all equipment works well under heavy load, for example, some UBIQUITI models are able to provide work for 10-15 devices at the same time, the 16th user will even crack and will not connect in Life.
As a recommendation, look in the direction of equipment that, in terms of Sensitivity / Noise Suppression / Loading, will be more powerful. Mariot and Hyatt put on Ruckus.