Canon EOS REBEL T7I Wi-Fi (Wireless Communication) Function Instruction Manual page 49

The camera cannot be connected to two or more smartphones at the

same time.
When touching the smartphone to the camera, be careful not to drop the

camera or smartphone.
Do not touch the smartphone to the camera with too much force. Doing

so can scratch the camera or smartphone.
Just holding the smartphone close to the camera may not establish a

connection. Be sure to touch the camera with the smartphone so that
they come into contact with each other.
Recognition may be difficult depending on the smartphone. Touch slowly

while changing the position or rotating horizontally. If connection is not
established, keep the camera and smartphone together until the camera
screen is updated.
Another application on the smartphone may start depending on how you

touch. Check the position of the p mark, then touch again.
When touching the smartphone to the camera, do not leave anything

between the camera and smartphone. In addition, when a case is
attached to the camera or smartphone, Wi-Fi connection with the NFC
function may not be possible.
A Wi-Fi connection cannot be established with the NFC function between

this camera and a smartphone while they are connected via Bluetooth.
To connect this camera to an NFC-compatible smartphone via Wi-Fi, the

smartphone's Wi-Fi and NFC functions must be enabled.
NFC Function Cautions
A Wi-Fi connection cannot be established with the NFC function between

this camera and another NFC-compatible device such as a camera or
printer.
A Wi-Fi connection cannot be established with the NFC function while

shooting with this camera, when there is no card, when the LCD monitor
is closed with the screen facing inward, or while the camera is connected
to another device with an interface cable.
Wi-Fi Connection to an NFC-compatible Smartphone
49