Nextcloud is spitting me out - bruteforce attempt

Nextcloud version (eg, 20.0.5): 25.05.
Operating system and version (eg, Ubuntu 20.04): Sysnology PHP version _(eg, 7.4)_: 8.0`

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

$CONFIG = array (
  'instanceid' => '***',
  'passwordsalt' => '***',
  'secret' => ***',
  'trusted_domains' => 
  array (
    0 => 'sub.nextclouddomain.de',
    1 => 'localhost',
    2 => '192.168.178.30',
  ),
  'trusted_proxies' => '192.168.178.30',
  'overwriteprotocol' => 'https',
'overwritehost' => 'sub.nextclouddomain.de',  
'datadirectory' => '/volume1/nextcloudData',
  'dbtype' => 'mysql',
  'version' => '25.0.5.1',
  'overwrite.cli.url' => 'https://sub.nextclouddomain.de',
  'dbname' => '***',
  'dbhost' => 'localhost:3306',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => '',
  'dbpassword' => 'Password',
  'installed' => true,
  'memcache.local' => '\\OC\\Memcache\\APCu',
  'default_phone_region' => 'DE',
  'mail_from_address' => 'nextcloud',
  'mail_smtpmode' => 'smtp',
  'mail_sendmailmode' => 'smtp',
  'mail_smtpsecure' => 'ssl',
  'mail_domain' => '***',
  'mail_smtpauthtype' => 'LOGIN',
  'mail_smtpauth' => 1,
  'mail_smtphost' => '***',
  'mail_smtpport' => '465',
  'mail_smtpname' => '***,
  'mail_smtppassword' => 'Password,
  'filelocking.enabled' => 'false',
  'loglevel' => 3,
  'app_install_overwrite' => 
  array (
    0 => 'files_texteditor',
    1 => 'issuetemplate',
  ),
  'maintenance' => false,
  'share_folder' => '/Freigaben',
  'theme' => '',
  'allow_local_remote_servers' => true,
);

Hello,
I have a fiber connection among other things with an ipv6.
On my Nas which is on its own network I have installed nextcloud 25.
Since a short time I have to delete my Brutforce attemps in my php table again and again. II lock myself out both on my own network and externally. Unfortunately I do not know why. Attached is my config. Does anyone have any idea what the problem is?