My friend is looking to extend the wifi coverage of his restaurant, the router is the TP-Link TD-W9970 which is in the office at the front and it provides good signal at the front and middle however there is no signal at the back or the function room upstairs so I'm wondering whether wifi powerline adapter (TP-Link TL-WPA4220T or devolo dLAN 500 Wi-Fi Powerline) or a mesh system (Tenda Nova MW3) will work better to extend the signal?