Canon EOS REBEL T7I Wi-Fi (Wireless Communication) Function Instruction Manual page 142

Responding to Error Messages
23: Device with same IP address exists on selected
network
What to check on the camera
Do the camera and another device connected via Wi-Fi to the

same network have the same IP address?
Change the camera's IP address to avoid using the same address

as another device on the network. Otherwise, change the IP
address of the device that has a duplicate address.
If the camera's IP address is set to [Manual setting] in network

environments using a DHCP server, change the setting to [Auto
setting] (p.121).
Responding to Error Messages 21 - 23
Check also the following points when responding to errors numbered
21 - 23.
Are the camera and the access point set to use the same password for
authentication?

This error occurs if the passwords do not match when the authentication
method for encryption is set to [Open system]. The setting is
case-sensitive, so check upper- and lower-case characters. Make sure
that the correct password for authentication is set on the camera
(p.120).
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