Eric has reported on OpenWrt's bug tracking system[1], that he's not
able to use USB devices on his WNDR3400v2 device after the boot, until
he turns on GPIO #21 manually through sysfs.
1. https://bugs.openwrt.org/index.php?do=details&task_id=2170
Signed-off-by: Petr Štetiar <ynezz@true.cz>
