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: 03.05.2024 @ 23:03
Script: /memberslist.php?letter=&sid=4ab617e244e180a8acd8eebc84c2219f&sortby=email&order=ASC
Referer: http://stc-board.de/memberslist.php?letter=&sid=4ab617e244e180a8acd8eebc84c2219f&sortby=email&order=ASC