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: 04.05.2024 @ 16:17
Script: /memberslist.php?letter=&sid=ccc2199742c0ff6e80bffab8f4ea2680&order=DESC&sortby=userposts&page=4
Referer: http://stc-board.de/memberslist.php?letter=&sid=ccc2199742c0ff6e80bffab8f4ea2680&order=DESC&sortby=userposts&page=4