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 @ 20:42
Script: /attachment.php?attachmentid=549&sid=6266d969f20b4b6032ab2fcd2306aff8
Referer: http://stc-board.de/attachment.php?attachmentid=549&sid=6266d969f20b4b6032ab2fcd2306aff8