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 @ 01:05
Script: /calendar.php?month=3&year=2024&sid=a7fac6a2f5fc015c135ab7d43a2df8e6
Referer: http://stc-board.de/calendar.php?month=3&year=2024&sid=a7fac6a2f5fc015c135ab7d43a2df8e6