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: 09.05.2024 @ 13:36
Script: /attachment.php?attachmentid=136&thumbnail=1&sid=6d5843c375e2f36d1acc50ce36bc931d
Referer: http://www.stc-board.de/attachment.php?attachmentid=136&thumbnail=1&sid=6d5843c375e2f36d1acc50ce36bc931d