Is function, thx.
i put this in System-Schedule Tasks and reboot.
System: GL-MT300N-V2
# leds off
*/5 21-23,0-5 * * * find /sys/devices/platform/leds/leds \! -path '*usb*' -name brightness -exec sh -c 'echo 0 > {}' \;
# leds on
*/5 6-20 * * * find /sys/devices/platform/leds/leds \! -path '*usb*' -name brightness -exec sh -c 'echo 255 > {}' \; && /etc/init.d/led start