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: 06.05.2024 @ 01:55
Script: /attachment.php?attachmentid=423&sid=a8c6f1d25feaba1037b29f868d045157
Referer: http://stc-board.de/attachment.php?attachmentid=423&sid=a8c6f1d25feaba1037b29f868d045157