SQL-DATABASE ERROR

Database error in WoltLab Burning Board: Link-ID == false, connect failed
mysql error: Unknown MySQL server host 'mis47.de' (110)
mysql error number: 2005
Date: 27.07.2021 @ 13:05
Script: /register.php?sid=ba0628bb75e4909af86e4d05c6be1dce
Referer: