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 @ 16:16
Script: /calendar.php?sid=90d837f2f9366b5909dc7a1eebba881e
Referer: http://stc-board.de/calendar.php?sid=90d837f2f9366b5909dc7a1eebba881e