From time to time, Mikrotik has problems with data transfer over Wi-Fi, perhaps due to torrents, how to win?

Question

WiFi

CAPSMAN is configured with a working and guest network, the number of access points is 10 pcs. Everything works without comment, but sometimes something incomprehensible happens - clients connect to points, the signal level is high, but there is no transmission at all on some clients. Clients are close enough to points - about 10 meters. The signal strength on the client is high. However, despite the presence of a client connection to the point, pings do not pass, the client cannot access the Internet, cannot even get an IP from DHCP (from DC). The number of clients connected to this point at this moment is no more than 3x. In the evening, when there is no one in the office, the network always works perfectly, the transmission speed both within the network and with the Internet is excellent. The paradox is that the user with the best signal strength received the most complaints and I actually observed this situation, albeit remotely. I didn’t see what was on the laptop, but I saw that the client was registered on the network, but the data transfer was zero, I couldn’t reach him.
In addition to the main network, there was also a guest network. There was a suspicion that clients from the guest network were running torrents or something similar.
Retreat
(In a completely different network, without CAPSMAN but with Wi-Fi, a similar problem is observed, only all clients connected to the point fall off there. It was experimentally established that MediaGet was to blame, as soon as one of the users launched it, everything fell off soon clients (of whom there were also about three).)
For the sake of the experiment, it was decided to disable all clients of the guest network (the password was simply changed). The situation has become much better, complaints about the lack of access to the network have ceased. A month passed, no one was allowed into the guest network, but again a complaint was received about the lack of access to the Internet, all from the same user with the best signal, I could not verify this, it seemed that the channel did not fall in the logs and no one else complained about the lack Internet, I think that the problem is all from the same area, but I don’t know where to look?
What is the reason for this behavior and can something be done about it?

Answer 1

I think we need to start with a "control sample".
Those. from a "clean" laptop (without a bare, properly configured OS). Let it cling to the same point and the same network as the problem client / clients.
And already proceeding from the state of the control laptop, think further.
And then while the information "one grandmother said," but for the diagnosis is death.
PS Well, no one has canceled shapers yet.

Answer 2

How are network access points connected? ethernet or repeaters?
Go to the admin panel of the access points and look at the load and the number of connections, if the reason is due to a large number of connections or memory overflow at the point, you will notice this already from the operation of its interface.
There is a chance that one of the access points or the switch between the problematic router and the Internet gateway is buggy, for example, due to overheating.
in general, look not only at the access points themselves for the problem.