/etc/rc.local

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

# Wi-Fi power management OFF
iwconfig wlan0 power off

exit 0

chmod +x /etc/rc.local

systemctl daemon-reload

systemctl start rc-local