No Ethernet cable is required. The idea for extending your Wi-Fi outdoors is to place the mesh router central in your home and put the satellite unit, or units, as close to the exterior as possible.

If you need to extend your Wi-Fi over a larger area ... you get a strong connection without having to deal with running long Ethernet cables across your home. If you don't mind dealing with ...

You just plug one of two small boxes into an outlet near your router and connect it using an Ethernet cable, then you plug in the other into an outlet where you want to extend your internet to.