出于安全原因，我将公共访问设置为“否”。
我有堡垒服务器（公共），was服务器（专用），和rds（专用）在不同的子网。
当我尝试从was服务器连接rds时，它工作正常。命令包括：

mysql -u <user>  -p -h <rds address> m -P 3306

其他隧道方案（堡垒）也在发挥作用。
但当我在was服务器上运行我的web应用程序时，它无法连接到我的rds。
错误消息如下：

at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:358) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:477) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:560) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) ~[HikariCP-3.4.5.jar!/:na]
        at org.hibernate.engine.jdbc.connections.internal.DatasourceConnectionProviderImpl.getConnection(DatasourceConnectionProviderImpl.java:122) ~[hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcEnvironmentInitiator.java:180) ~[hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:68) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:176) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:118) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1224) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1255) [hibernate-core-5.4.23.Final.jar!/:5.4.23.Final]
        at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) [spring-orm-5.3.1.jar!/:5.3.1]
        at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.3.1.jar!/:5.3.1]
        at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:409) [spring-orm-5.3.1.jar!/:5.3.1]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[na:1.8.0_272]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) ~[na:1.8.0_272]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) ~[na:1.8.0_272]
        at java.lang.Thread.run(Thread.java:748) ~[na:1.8.0_272]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_272]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_272]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_272]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_272]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.NativeSession.connect(NativeSession.java:144) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:850) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        ... 34 common frames omitted
Caused by: java.net.SocketTimeoutException: connect timed out
        at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_272]
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_272]
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_272]
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_272]
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_272]
        at java.net.Socket.connect(Socket.java:607) ~[na:1.8.0_272]
        at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        ... 36 common frames omitted