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: 28.04.2024 @ 12:16
Script: /calendar.php?month=2&year=2024&sid=a6154f75d501da0e23abd3f1f9e0acf8
Referer: http://stc-board.de/calendar.php?month=2&year=2024&sid=a6154f75d501da0e23abd3f1f9e0acf8