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 @ 23:16
Script: /register.php?sid=017ea5dd14283fe2d0b8fe5c8f3d5205
Referer: http://stc-board.de/register.php?sid=017ea5dd14283fe2d0b8fe5c8f3d5205