@IsaMath Hello, 

May I know did you try factory reset the range extender  as below and check if you could see the default SSID on the laptops and phones. 

reset : with RE powered on , use a pin to keep press the reset hole until all the Leds flash once

If the default SSID, 'TP-LINK Extender', or 'Range Extender ' still does not show up on all the devices, it is possible the range extender is defective, you could contact the local retailer or show to check warranty for it, thank you for your understanding.