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: 11.05.2024 @ 22:17
Script: /calendar.php?action=eventcalendar&sid=d215b9a0ab5f0178a60c09fa6dbd606c
Referer: http://stc-board.de/calendar.php?action=eventcalendar&sid=d215b9a0ab5f0178a60c09fa6dbd606c