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: 02.05.2024 @ 00:16
Script: /memberslist.php?letter=&sid=6e514450587162d3c32fd1e968358651&sortby=regdate&order=ASC
Referer: http://stc-board.de/memberslist.php?letter=&sid=6e514450587162d3c32fd1e968358651&sortby=regdate&order=ASC