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: 08.05.2024 @ 23:01
Script: /thread.php?goto=firstnew_thread&threadid=875&sid=4ad944d3f2dcfd36f422e875b32c90ab
Referer: http://www.stc-board.de/thread.php?goto=firstnew_thread&threadid=875&sid=4ad944d3f2dcfd36f422e875b32c90ab