Why you may see MAC addresses you don't recognize on your network
Some users have noticed that when introducing a TP-Link range extender, they now see additional devices that they normally didn't.
An important function that our range extenders do is to generate a virtual MAC address for devices that connect to our extender. This is known as "Proxy Mode" which aims to be a feature to be universally compatible with any router.
Below shows a RE350 that has supplied virtual MAC addresses:
The benefit is for compatibility, but on the other end, can cause confusion especially when doing MAC filtering.