Canon EOS-1D X Mark III Advanced User's Manual page 523

Steps on the smartphone (3)
13.
Tap a Camera Connect function.
Terminating Wi-Fi connections
Disconnect by tapping [
Terminating the Wi-Fi connection will switch the camera to the Bluetooth connection.
Reconnecting
To reconnect via Wi-Fi, start Camera Connect and tap the function you will use.
In iOS, tap [Join] when a message is displayed to confirm camera
connection.
After the devices are connected via Wi-Fi, a screen for the selected
function is displayed on the smartphone.
The Bluetooth and Wi-Fi icons are now displayed on the main Camera
Connect screen, after you return to that screen.
The camera's <
] on the Camera Connect screen.
> lamp is lit in green.
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