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 @ 01:18
Script: /attachment.php?attachmentid=239&sid=e0f5d19f577587cbccbb5fe0c69b8d4e
Referer: http://stc-board.de/attachment.php?attachmentid=239&sid=e0f5d19f577587cbccbb5fe0c69b8d4e