Check your current power save state:
cat /etc/NetworkManager/conf.d/*.conf
Unless it has been previously changed, it should read:
[connection]
wifi.powersave = 3
In this context, 3 indicates that the Network Manager will use power saving. Let’s change it to 2, indicating that the system will not use power saving. From the terminal:
sudo sed -i 's/3/2/' /etc/NetworkManager/conf.d/*
sudo systemctl restart NetworkManager.service
https://askubuntu.com/questions/1294591/how-to-permanently-set-wi-fi-power-management-flag-to-off: Linux WiFi disable power mode