In the PHP code, in the turn off command, remove $a code- exec(“echo 18 > /sys/class/gpio/unexport”);, as you have in the first switch and now already I works.
Katika PHP code, katika zima amri, Ondoa $a msimbo- Exec(“mwangwi 18 > /SYS/darasa/gpio/unexport”);, kama unaweza kuwa kwenye swichi ya kwanza na sasa ni kazi mimi.