Database error in vBulletin :

mysql_connect(): Can't connect to MySQL server on 'mysqlucoolbbsmaster' (104)
/data/product/ucool/production/bbs/a/includes/class_core.php on line 317

MySQL Error   : 
Error Number  : 
Request Date  : Monday, December 4th 2023 @ 03:36:02 PM
Error Date    : Monday, December 4th 2023 @ 03:36:11 PM
Script        : http://forum.ucool.com/forumdisplay.php?35-Technical-Support
Referrer      : 
IP Address    : 18.206.13.203
Username      : 
Classname     : vB_Database
MySQL Version :