I try to use the Radius account to set the 3rd party authentication to login KN4116VA.

Most of the accounts use E-mail address as the account name.

When I use some accounts to login, but it fails.

After verifying, the accounts with less character could pass.  Is there any limitation of the user account?

It's because of the hardware limitation, the max length of the user account is up to 16 characters.

No matter it's the account that creates directly in KN unit or it's from 3rd party authentication, the limitation is the same.

If the 3rd party authentication account is over 16 characters, it will make the communication unstable or it will be refused by KN unit.