Canon EOS 5D Mark IV Instruction Manual page 118

Transferring Images Individually
Automatic Retransfer if Transfer Fails
Once the cause of the error is eliminated, the images whose transfer
previously failed will be retransferred automatically. With this option
activated, transfer is attempted again automatically after a failure, not
only when automatic transfer is used, but also when captured images
are transferred via FTP. Note that when you cancel image transfer, or
turn off the camera, the image will not be retransferred automatically.
See page 119 and transfer the image.
118
If transfer fails, the Wi-Fi function icons on
the LCD panel and LCD monitor blink
(p.23). In this case, press the <M>
button, select [Communication settings]
under the [54] tab, then press <0>. When
the screen shown on the left is displayed,
check the error code number and see page
148 to eliminate the cause of the error.