Several unknown wireless devices on my network.
IPv4 Address / Name 192.168.1.139 / unknown849ca693f734
IPv4 Address / Name 192.168.1.238 / unknown28f366566c89
IPv4 Address / Name 192.168.1.89 / unknown142d275de73a
Sometimes printers will show up as unknown. Also media devices like Apple TV or Roku may show up as unknown. Security cameras may show up as unknown as well.
Do you have a WiFi password? Is it a secure password or is it something easy to figure out?
If you're uncertain what these devices are after further investigation, I suggest changing your WiFi password to something very strong.