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: 02.05.2024 @ 01:57
Script: /memberslist.php?letter=&sid=a503f24f1b8f899e08d88a5d84844c58&order=DESC&sortby=userposts&page=2
Referer: http://stc-board.de/memberslist.php?letter=&sid=a503f24f1b8f899e08d88a5d84844c58&order=DESC&sortby=userposts&page=2