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: 12.05.2024 @ 00:57
Script: /newthread.php?boardid=18&sid=1dc53a6ffda5bd6fe836f89f1514860e
Referer: http://www.stc-board.de/newthread.php?boardid=18&sid=1dc53a6ffda5bd6fe836f89f1514860e