Canon EOS 6D Instruction Manual page 341

Using Eye-Fi Cards
Cautions for Using Eye-Fi Cards
If [53: Wi-Fi] is set to [Enable], image transfer with an Eye-Fi card is not
possible.
If " " is displayed, an error occurred while retrieving the card
information. Turn the camera's power switch off and on again.
Even if [Eye-Fi trans.] is set to [Disable], it may still transmit a signal. In
hospitals, airports, and other places where wireless transmissions are
prohibited, remove the Eye-Fi card from the camera.
If the image transfer does not function, check the Eye-Fi card and
computer settings. For details, refer to the card's instruction manual.
Depending on the wireless LAN's connection conditions, the image
transfer may take longer or it may be interrupted.
Because of the transmission function, the Eye-Fi card may become hot.
The battery power will be consumed faster.
During the image transfer, auto power off will not take effect.
If you insert a wireless LAN card other than an Eye-Fi card, [Eye-Fi
settings] will not appear on the menu. Also, the transmission status icon
<H> will not appear on the LCD monitor.
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