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: 28.04.2024 @ 13:54
Script: /register.php?sid=4c1a268f47dd0a0d9d6d02a93f6ef050
Referer: http://stc-board.de/register.php?sid=4c1a268f47dd0a0d9d6d02a93f6ef050