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 @ 01:51
Script: /attachment.php?attachmentid=1166&thumbnail=1&sid=70878e6641c11511b9ab3b2d62f637f1
Referer: http://stc-board.de/attachment.php?attachmentid=1166&thumbnail=1&sid=70878e6641c11511b9ab3b2d62f637f1