Hello @asgshe 

The theoretical Wi-Fi range of tp-link range extender is about 15-20 meters, but Wi-Fi signal /Wi-Fi range could be dramatically degraded through thick walls, a Wi-Fi extender may not transmit further through walls when compared with your old router.  If there are thick walls between Router and extender,  you may consider

1)  extend signal through wired connection / Ethernet cable 

You could consider a Router or WiFi Range Extender and use it in the AP mode ( AP wired to main router through Ethernet cable) 

How to configure the TP-Link wireless router as Access Point?

How to setup Access Point Mode of Range Extender?

2) if your house is under the same power line/ same power meter, you could consider a Powerline KIT with Wi-Fi feature :
https://www.tp-link.com/home-networking/powerline/?filterby=5793%7C5794%7C5795

Hope this helps.