Canon MX720 Series Online Manual page 185

4. Key ID:
Select the Key ID (index) set to the access point.
Note
When the printer is connected to an AirPort Base Station via a LAN:
When the printer is connected to an AirPort Base Station via a LAN, confirm the
settings in Wireless Security of AirPort Utility.
Select 64 bit if WEP 40 bit is selected for the key length in the AirPort Base
Station.
Select 1 for Key ID:. Otherwise your computer will not be able to communicate
with the printer via the access point.
5. Authentication:
Select the authentication method to authenticate the printer's access to the access point.
Normally, select Auto. If you want to specify the method manually, select Open System or
Shared Key according to the setting of the access point.
7. Click OK.
Important
If the printer cannot communicate with the computer after the encryption type of the printer
was switched, make sure that encryption types for the computer and the access point
matches that set to the printer.