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 @ 00:30
Script: /thread.php?threadid=766&threadview=0&hilight=&hilightuser=0&sid=13b96c4f89c375bf6b9e1c807442d86c
Referer: http://stc-board.de/thread.php?threadid=766&threadview=0&hilight=&hilightuser=0&sid=13b96c4f89c375bf6b9e1c807442d86c