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: 05.05.2024 @ 18:04
Script: /board.php?boardid=53&sid=2fa0c9b091e1f69a5e8a51d82ec0ccbc
Referer: http://stc-board.de/board.php?boardid=53&sid=2fa0c9b091e1f69a5e8a51d82ec0ccbc