vi /usr/lib/systemd/system/wifi_disable_powersave.service
[Unit]
Description=Disable WiFi power save mode
After=sys-subsystem-net-devices-wlan0.device
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/sbin/iw dev wlan0 set power_save off
[Install]
WantedBy=sys-subsystem-net-devices-wlan0.device
systemctl daemon-reload
systemctl enable wifi_disable_powersave