https://support.huaweicloud.com/intl/en-us/eu-west-0-usermanual-rds/rds_faq_0056.html
How Can I Prevent Untrusted Source IP Addresses from Accessing RDS?_Network Security_FAQs_ User...
After you enable public accessibility, your EIP DNS and database port may be obtained by malicious personnel. To protect your information including your EIP,...
ip addressesrds networksecurity faqspreventuntrusted
https://www.alibabacloud.com/help/en/rds/developer-reference/api-rds-2014-08-15-modifydbinstancenetworktype
Use ModifyDBInstanceNetworkType to change the network type from classic to VPC - ApsaraDB RDS -...
Switch your RDS instance from classic network to a VPC using the `ModifyDBInstanceNetworkType` API, with a full parameter reference and error code examples.
the networkusechangetypeclassic