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: 29.04.2024 @ 01:18
Script: /board.php?boardid=55&page=1&daysprune=1000&sortfield=starter&sortorder=ASC&sid=1b78ed853d75125d88b9e8b5c4be32ad
Referer: http://stc-board.de/board.php?boardid=55&page=1&daysprune=1000&sortfield=starter&sortorder=ASC&sid=1b78ed853d75125d88b9e8b5c4be32ad