SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: Connection refused
mysql error number: 2002
mysql version: unknown
php version: 5.6.40-57+0~20211119.60+debian9~1.gbp8a9bd1
Date: 28.04.2024 @ 11:02
Script: /board.php?boardid=18&daysprune=1000&sortfield=starter&sortorder=ASC&sid=330134f430c6740f74db7122d58e61a8&page=3
Referer: http://stc-board.de/board.php?boardid=18&daysprune=1000&sortfield=starter&sortorder=ASC&sid=330134f430c6740f74db7122d58e61a8&page=3