Before resetting the TP-Link extender, you must restart the range extender and check out the reset key that you can find at the bottom of the extender. To perform the TP-Link extender reset process, look out for a toothpick, pen, or paperclip, preferably non-metallic and then push the reset key and hold it for 10-15 seconds. Now, ensure that power is on for the range extender, and when the lights are blinking on the extender, it means the reset process has begun. Wait for 2 minutes and reset it again. With this, your TP-Link expender has been restored to the factory default settings.
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With the Range Extender powered on, use a pin to press and hold the RESET button (about 8 seconds) until the System LED becomes quick-flash from slow-flash. And then release the button and wait the Range Extender to reboot to its factory default setting
Regards,
Willjoe