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: 06.05.2024 @ 00:07
Script: /register.php?sid=35c1d894d75cf650d6cc5b6f8adec96b
Referer: http://stc-board.de/register.php?sid=35c1d894d75cf650d6cc5b6f8adec96b