Amazon.com: TP-Link Powerline WiFi Extender - Add-on Single Adapter, Ethernet over Powerline, Plug & Play, Compatible with all TP-Link powerline adapters with different speed, AV600 with N300 WiFi(TL-WPA4220) : Everything Else
How to upgrade TP-Link Powerline Adapters
TP Link TL-PA511 Powerline Adapter Gigabit AV500 | eBay