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 @ 20:07
Script: /attachment.php?attachmentid=900&thumbnail=1&sid=1a86dd49bb2d473f5e8518d416a51641
Referer: http://stc-board.de/attachment.php?attachmentid=900&thumbnail=1&sid=1a86dd49bb2d473f5e8518d416a51641