Unrecognized devices

I noticed recently that when my internet drops, there is an unrecognized device connected to my internet. This has happened 10 to 12 times. I’m not always able to catch it connected but, I do pause it each time. It’s always a device called “Guangzho- (insert last four of MAC address). It always has a different MAC address but always the same device name. A little research on my part concluded that “Guangzhou is a province in China. Has anyone else had this issue? And it’s always connected through Ethernet.