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: 07.05.2024 @ 20:20
Script: /attachment.php?attachmentid=1164&thumbnail=1&sid=6fac3cea2693b363ce01a8b8b3c83d0a
Referer: http://stc-board.de/attachment.php?attachmentid=1164&thumbnail=1&sid=6fac3cea2693b363ce01a8b8b3c83d0a