AuthUnknown error when running code in Windows Service

[umar-ulabs]

The connection fails when using public IP or domain of the AD server
Everything works fine except when code is running inside a windows service and the server address is public one(port forwarding to 389 or 636).
The error return is AuthUnknown which is result code 86
Following are the connection settings:
var connection = new LdapConnection();
var isSecure = _config.UseSSL || _config.Port == 636 || _config.Port == 3269;
connection.Connect(_config.Server, _config.Port, isSecure ?
LdapSchema.LDAPS : LdapSchema.LDAP);
if (_configUseSSL)
{
connection.TrustAllCertificates();
}

            var cred = new LdapCredential();
            cred.UserName = _config.Username;
            cred.Password = _config.Password;
            await connection.BindAsync(LdapAuthType.Negotiate , cred);

Thanks

[flamencist]

Check requirements:

• Your client machine should be joined to domain for using negotiate auth type
• need specify realm(domain) , username and password for login as another user
  Or you could use other options: ldap simple auth or impersonate under domain user

[umar-ulabs]

Right. What I did is try catch for couple of auth types. If one fails ,use different auth type. It seems working well that way. The OR on auth types didnt work like Auth Type Negotiate | Auth Type Simple, but using try catch to try different auth types seems working for now

[flamencist]

Yes. Its lightweight library without most features like cache or reliability