Do robot mowers need Wi-Fi to work?

Not usually. Very few mowers need your home Wi-Fi to cut the grass, but many need some kind of connection for setup and for the extras.

Wired mowers (the ones that follow a perimeter wire) often work with no connection at all. Many have a keypad or buttons for setting a schedule, and the app, if there is one, is an optional extra.

Wire-free mowers almost always need a phone app, because the app is how you map the lawn. During mapping your phone talks to the mower over Bluetooth or Wi-Fi. After that, how much connectivity matters depends on the navigation:

• Network RTK mowers get their satellite corrections over the internet, normally through a built-in 4G connection rather than Wi-Fi. They need decent mobile coverage at the lawn, not a strong router signal.
• LiDAR and camera mowers work out their position on board, so they don't need a connection to navigate.
• Mowers with their own RTK aerial get corrections from that aerial locally.

Wi-Fi is mainly useful for controlling the mower from the house, receiving software updates and getting alerts. At the bottom of a long garden it may not reach, which is one reason built-in 4G has become common on wire-free models.

Our guide to network RTK and 4G explains how to check coverage before you buy.