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: 05.05.2024 @ 12:14
Script: /board.php?boardid=18&daysprune=1000&sortfield=lastposttime&sortorder=DESC&sid=4c941b16cc2575c57920ac6fb3c372f0&page=2
Referer: http://www.stc-board.de/board.php?boardid=18&daysprune=1000&sortfield=lastposttime&sortorder=DESC&sid=4c941b16cc2575c57920ac6fb3c372f0&page=2