Canon LBP7780CX User Manual page 411

When using TTLS
Select the internal TTLS authentication method.
(1) Select [MSCHAPv2] or [PAP].
8
Click [Change User Name/Password...].
When using the log in name entered in Step 6 as the user name
Select the [Use Login Name as User Name] check box.
9
Enter user name.
Up to 24 alphanumeric characters can be entered.