You can use the Ethernet ports on your Orbi WiFi system's router or satellites to connect client devices like smart TVs, game consoles, and desktop computers. You might want to connect devices to your Orbi satellites' Ethernet ports if you need the performance and stability of a wired connection, but it's impractical to run a very long Ethernet cable back to your Orbi router.
You can also use your Orbi's Ethernet ports to set up Ethernet backhaul between your router and satellites. Ethernet backhaul might be useful if your router and satellites need to be placed very far apart, or if your home's construction causes problems with WiFi signal strength. For more information, see What is Ethernet backhaul and how do I set it up on my Orbi WiFi System?