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: 12.05.2024 @ 00:55
Script: /memberslist.php?letter=&sid=43242dac64a9e70a7c1b7c3a4f5d752c&order=DESC&sortby=userposts&page=2
Referer: http://stc-board.de/memberslist.php?letter=&sid=43242dac64a9e70a7c1b7c3a4f5d752c&order=DESC&sortby=userposts&page=2