@Vilojona 

Hello，

Did you press the WPS button on your router and both the WI-FI button on the WPA4220? If so, you may copy the wifi network name of your router and at this time the WPA4220 will have the same network name and password with your router.

Here is an instruction you can refer to pair the units again:

https://www.tp-link.com/en/support/faq/1617/

Please note that you need to pair them in the same room with your router.

After paring them, if you can see the House LED light lit up on both units, you don't need to press the PAIR button for 10 seconds. This way will reset the product and all the settings will turn to factory defaults.

If you need further help, please tell me the LED light on the product.

May it help and have a nice day!