Mikrotik PL7411-2nD PWR-Line AP

Quick overview from the supplier:

Mikrotik PL7411-2nD PWR-Line AP // The PWR-Line AP is a small Wi-Fi access point, made as an accessory to your existing network, for places, where your signal or your cable is unable to reach. Unit comes with Type C power plug (commonly used in Europe, South America & Asia). Especially useful in homes with thick walls, where you can extend Wi-Fi coverage to those rooms, where signal is poor, without having to re-wire your house. Simply plug this device directly into one of the LAN ports of your MikroTik router, and add another one somewhere further in your premises. They will link together through the power lines. You can install up to eight PWR-LINE devices to further build your network.