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: 08.05.2024 @ 09:51
Script: /memberslist.php?letter=&sid=14d90605e7e9c5191d669fadc04cd43d&order=ASC&sortby=u.avatarid&page=2
Referer: http://stc-board.de/memberslist.php?letter=&sid=14d90605e7e9c5191d669fadc04cd43d&order=ASC&sortby=u.avatarid&page=2