Canon EOS-1D X Mark III Advanced User's Manual page 532

Steps on the smartphone
17.
Operate the smartphone to establish a Wi-Fi connection.
18.
Start Camera Connect and tap the camera to connect to via Wi-Fi.
Activate the smartphone's Wi-Fi function, then tap the SSID (network
name) you checked in step 16.
In the password field, enter the password you checked in step 16, then
tap [Join].
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