ApsaraDB RDS:What do I do if I fail to connect to an ApsaraDB RDS instance?

Common connection errors

The following tables describe common connection errors for RDS instances that run different engines and the solutions to these errors.

Issues that cause failures to connect to RDS instances by using DMS

You can see the following documentation to handle the errors that occur when you connect to RDS instances by using DMS: Use DMS to log on to an ApsaraDB RDS for SQL Server instance.

Issues that cause failures to connect an ECS instance to an RDS instance over an internal network

• Before you connect an ECS instance to an ApsaraDB RDS instance by using the internal endpoint of the ApsaraDB RDS instance, you must add the private IP address of the ECS instance to an IP address whitelist of the ApsaraDB RDS instance.

  Note

  • For more information, see Configure an IP address whitelist for an RDS for SQL Server instance.

  • If you add the public IP address of the ECS instance to an IP address whitelist of the ApsaraDB RDS instance, you cannot connect the ECS instance to the ApsaraDB RDS instance by using the internal endpoint of the ApsaraDB RDS instance.

• You can connect an ECS instance to an ApsaraDB RDS instance over an internal network only when these instances reside in the same region. These instances can reside in the same zone or different zones of the same region.

  • Make sure that the ECS instance and the ApsaraDB RDS instance reside in the same region.

    1. View the region in which the ECS instance resides.

    2. View the region in which the ApsaraDB RDS instance resides.

  • If the ECS instance and the ApsaraDB RDS instance reside in different regions, these instances cannot directly communicate with each other over an internal network. In this case, you can use one of the following methods to resolve the issue:

    • Method 1:

      • Release the ECS instance. Then, purchase an ECS instance that resides in the same region as the RDS instance.

      • Release the RDS instance. Then, purchase an RDS instance that resides in the same region as the ECS instance.

    • Method 2: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an RDS for SQL Server instance. This method cannot deliver optimal performance, security, or stability.

Check network types

1. Make sure that the ECS instance and the ApsaraDB RDS instance both reside in VPCs or in the classic network.

   • View the network type of the ECS instance.

   • View the network type of the RDS instance.

2. If one instance resides in the classic network and the other instance resides in a VPC, use one of the following methods to resolve the issue:

   • Methods suitable in scenarios in which the ECS instance resides in a VPC and the RDS instance resides in the classic network:

     • Method 1: Change the network type of the RDS instance from the classic network to the VPC in which the ECS instance resides. This is the recommended method.

       Switch the network type.

     • Method 2: Purchase an ECS instance that resides in the classic network. Take note that a VPC provides higher security than the classic network. We recommend that you use VPCs.

       Note

       ECS instances cannot be migrated from VPCs to the classic network.

     • Method 3: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an RDS for SQL Server instance. This method cannot deliver optimal performance, security, or stability.

   • Methods suitable in scenarios in which the ECS instance resides in the classic network and the RDS instance resides in a VPC:

     • Method 1 (recommended): Migrate the ECS instance from the classic network to the VPC in which the RDS instance to be connected resides. You can click View Connection Details on the right side of the Network Type page to view the ID of the VPC where the RDS instance resides. For more information, see Migrate an ECS instance.

     • Method 2: Change the network type of the RDS instance from a VPC to the classic network. Take note that a VPC provides higher security than the classic network. We recommend that you use VPCs.

     • Method 3: Use the ClassicLink feature to establish an internal network connection between the classic network-type ECS instance and the VPC-type RDS instance. For more information about the ClassicLink feature, see Enable ClassicLink.

       Note

       If the internal network connection between classic network-type ECS instance and the VPC-type RDS instance cannot be established after the ClassicLink feature is used, handle the issue based on the descriptions in Troubleshoot connection issues between a classic network and a VPC after you establish a ClassicLink connection.

     • Method 4: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an RDS for SQL Server instance. This method cannot deliver optimal performance, security, or stability.

3. If the ECS instance and the RDS instance both reside in VPCs, make sure that these instances reside in the same VPC.

   • View the VPC ID of the ECS instance.

   • View the network type of the RDS instance.

4. If the ECS instance and the RDS instance reside in different VPCs, use one of the following methods to resolve the issue:

   • Method 1: This is the recommended method. Migrate the RDS instance to the VPC in which the ECS instance resides. For more information, see Change the VPC and vSwitch.

   • Method 2: Create a Cloud Enterprise Network (CEN) instance to establish a connection between the two VPCs. For more information about CEN, see Use CEN to enable intra-region network communication.

   • Method 3: Connect the ECS instance to the RDS instance by using the public endpoint of the RDS instance. For more information about how to apply for a public endpoint for an RDS instance, see Apply for or release a public endpoint for an RDS for SQL Server instance. This method cannot deliver optimal performance, security, or stability.

5. If the ECS instance and the RDS instance reside in the same VPC and in the same region, the ECS instance can connect to the RDS instance by using the public endpoint rather than the internal endpoint of the RDS instance, and both the ping and telnet commands return connection failures, you can resolve the issue based on the descriptions in What do I do if an ECS instance cannot connect to an ApsaraDB RDS instance due to routing problems?

Issues that cause failures to connect to an RDS instance over the Internet

Make sure that the public endpoint of the RDS instance is used to connect to the RDS instance. You can view the public endpoint of the RDS instance on the Database Connection page in the ApsaraDB RDS console.

Make sure that the public IP address of the on-premises device that you want to connect to the RDS instance is added to an IP address whitelist of the RDS instance. If the on-premises device can be connected to the RDS instance after 0.0.0.0/0 is added to the IP address whitelist of the RDS instance, the IP address that you added to the IP address whitelist is incorrect. In this case, obtain the correct public IP address of an on-premises device based on the following topics and then add the public IP address to an IP address whitelist of the RDS instance. For more information about how to configure an IP address whitelist for an RDS instance, see Configure a security group for an ApsaraDB RDS for SQL Server instance.

For more information, see the following documentation:

• How do I obtain the public IP address of an external server or a client that is connected to an ApsaraDB RDS for SQL Server instance?

Reference

• Troubleshooting methods for RDS connection failures

Application scope

• ApsaraDB RDS