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: 11.05.2024 @ 23:48
Script: /memberslist.php?letter=&sid=12f255e74b53dc04cb5e9a17b0512fcb&order=DESC&sortby=userposts&page=2
Referer: http://stc-board.de/memberslist.php?letter=&sid=12f255e74b53dc04cb5e9a17b0512fcb&order=DESC&sortby=userposts&page=2