I bought the TL-WPA4220 KIT in Amazon in December 2018 and the wifi unit has stopped working properly for a couple of weeks now. It makes a high pitch noise continuously and the wifi signal keeps drop

My TP-LINK AV600 Powerline, model TL-WPA4220 KIT V4.0, has stopped working a month ago. The extender (TL-WPA4220) now makes a high pitch constant noise, almost like the dial-up adsl of 20 years ago. M