Why does Wi-Fi speed drop periodically? And what settings should be done?

Question

WiFi

Good day to all.

At home there is a Calic 813gv2-2 modem. The first year was great!
Now periodically, especially in the evening and at night, when everyone is at home, the Wi-Fi speed drops to 0. That TV, that various applications can show "No connection" for a minute, although Wi-Fi is connected.

In the router settings in the Wireless tab, there are now the following settings:

Screen settings

The wireless channel width is set to either 20 or 40. There is no 20/40 option.
I'm most interested in the last 3 checkboxes: Airtime Fairness, Frame Burst and PMF.
I read about them, but I wanted to ask those who know: is it worth enabling Airtime Fairness and Frame Burst at the same time? Does it work in practice?

Or if there is any advice on solving the problem, I will gladly listen to them.

ps according to the speedtest from the locale, it gives the declared speed. The problem is with Wi-Fi.

Answer 1

1. Consumer WiFi is not designed for a large number of simultaneous WiFi clients (for some, 3 is already a lot)
   
2. Maybe some neighbor's WiFi router can work at the same frequency and they can tritely conflict. With some kind of WiFi Analyzer on your phone, see which WiFi channels you have more free and put some channel of them in the router
   

PS Channel width is literally width. The ruler can be 20 cm, or maybe 40 cm. There cannot be a 20/40 ruler. An increase in the channel width may not give a positive effect, but rather ruin the life of your neighbors and you if they operate at close frequencies.

Answer 2

in practice - either a wonderful neighbor has settled, who sits on the same WIFI frequency, or, as an option, the wifi module in the router is overheating