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: 10.05.2024 @ 21:04
Script: /attachment.php?attachmentid=22&thumbnail=1&sid=8516e204521ad38cb1dbe5ab42bc2fc1
Referer: http://www.stc-board.de/attachment.php?attachmentid=22&thumbnail=1&sid=8516e204521ad38cb1dbe5ab42bc2fc1