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: 08.05.2024 @ 05:43
Script: /attachment.php?attachmentid=1164&thumbnail=1&sid=0f64484d040f3de2c5cbdfe738c3275a
Referer: http://stc-board.de/attachment.php?attachmentid=1164&thumbnail=1&sid=0f64484d040f3de2c5cbdfe738c3275a