Hi @Edwinge ,

Welcome to our community.

Yes, you can add the new unit as you paired the date extender before.

But if it doesn't work, please hard reset the first adapter, which is connected to the router, and the new extender:

For TL-PA4010 (the models which start with TL-PAxxxx), press and hold the Pair button for 15s until all LEDs turn off and then come back on.

For TL-WPA4220 (models beginning with TL-WPAxxxx), press and hold the Reset button for 10s. Release the button and all LEDs turn off. When the LEDs turn back on, the reset process is complete. 

Then configure the extender again: How to secure (pair) the Powerline Network