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: 04.05.2024 @ 11:17
Script: /calendar.php?sid=f1c5dec93af3ebdfe9f0d0c8db88b39b
Referer: http://stc-board.de/calendar.php?sid=f1c5dec93af3ebdfe9f0d0c8db88b39b