It looks that currently the authentication via the ldap-plugin works only via the DC User logon name (pre-Windows 2000). Is there a possibility to add support for use "Userlogon" name?
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Konfiguration at DC

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pre-Windows 2000 => fine:

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default => not fine:

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More Information from MS
https://docs.microsoft.com/en-us/windows/win32/secauthn/user-name-formats