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: 02.05.2024 @ 01:15
Script: /board.php?boardid=2&sid=86237cc0f37f1d5bf7e355b0cf67506d
Referer: http://stc-board.de/board.php?boardid=2&sid=86237cc0f37f1d5bf7e355b0cf67506d