Why doesn't Wi-Fi work on laptops?

Question

Computer networks

In general, the situation is as follows:
I was contacted by two absolutely unrelated people with the same problem - Wi-Fi does not work on their laptops at home. That is, they connect to the network, but the pages do not open, the files are not downloaded, or very slowly - 50-100 kbps. Other devices (phones, tablets, etc.) work fine.
The laptops are different - ASUS and Macbook Air
OS is the same on both - Win 10 edition 1909 (yes, Windows is also on the poppy - you need to work, but there is macOS there, by the way, wi-fi works fine in it)
Routers are different - Zyxel and Netgear, providers are different.
By the way, both laptops work fine in the office, the Zyxel router
What has been done:
1. Installed fresh updates
2. Updated drivers - delivered from offsite sites latest versions
3. Tried disabling antivirus, firewall, safe mode
4. Reset adapter settings, specifying IP both statically and via DHCP.
5. Reset and configure routers again, change SSID names, passwords.
6. Channels in routers changed.
7. Checking for viruses
In general, where to dig further?

Answer 1

See what they have on air. The 2.4 range is so littered that even wireless mice lag. Try 5GHz.

Answer 2

Speed ​​limits in the routers themselves? Type restrictions for unregistered devices in Zyxel