WiFi has a natural tendency for clients farther away or clients at lower data rates to monopolize the airtime and slow down overall performance. Airtime fairness helps to improve the overall network performance in these conditions.
Go to Settings > WiFi, and click on an SSID to open it. Turn on Multicast and Broadcast Control and add any exceptions (devices like printers, Airplay, or Chromecast).
The Airtime Fairness became available on wireless routers and access point more than a decade ago as the means to prevent older devices from slowing down the network.