Okay I have a AC 750 WiFi range extender, AV1000, power line edition. I need to mesh another unit into it to get better signal to the back of my house; and
TP-Link TL-WPA7517 AV1000 Gigabit Powerline ac WiFi Kit | NetXL
TP-Link AV1000 Gigabit Passthrough Powerline ac Wi-Fi Kit, Dual Band Speed Up to 1200 Mbps, Wi-Fi Extender/ Booster, Extra Power Socket, No Configuration Required (TL-WPA7617 KIT) : Amazon.co.uk: Computers & Accessories
How to add an extra powerline adapter to the existing powerline network with pair button | TP-Link