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 @ 11:32
Script: /memberslist.php?letter=&sid=3939c769f690ba3e3639072c93452997&order=ASC&sortby=userposts&page=2
Referer: http://stc-board.de/memberslist.php?letter=&sid=3939c769f690ba3e3639072c93452997&order=ASC&sortby=userposts&page=2