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 @ 12:56
Script: /register.php?sid=4b43a6c84d21b114d677365adc9d1edb
Referer: http://stc-board.de/register.php?sid=4b43a6c84d21b114d677365adc9d1edb