If the extender isn’t working as expected, we would first advise to perform a hard reset of the extender by holding down the small reset button on the bigger plug for 15 seconds and then re-pairing the extender.
Once you’ve re-paired the extender, you should also try placing them in different plug sockets as it could also be the internal wiring that’s affecting the extenders.
If you still have issues with the extender, we'd recommend contacting the TP LINK technical support team who will be able to look into this for you, you can contact them via live-chat here.
