You can identify the problem by following these steps:
Check if the cluster status is RUNNING. You cannot connect to the cluster if the cluster is being created, deleted, or when its IP whitelist is being updated.
Check if the IP address of your connection is included in the IP white list.
Test the connectivity of the port by running telnet in01-(uuid).(region).vectordb.zillizcloud.com 19530. If the issue remains unsolved after all above steps are tried, please submit a request.