This topic covers common causes of connection failures between Elastic Compute Service (ECS) instances and Lindorm instances over a private network, and how to resolve them.
Troubleshooting
Whitelist does not include the ECS private IP address
By default, Lindorm blocks all inbound connections. If the private IP address of your ECS instance is not on the Lindorm whitelist, connection attempts are rejected.
Add the private IP address of the ECS instance to the Lindorm instance whitelist. For instructions, see Configure a whitelist.
Security group rules block the connection
Security group rules on the ECS instance may block outbound traffic to the Lindorm private endpoint.
Create a security group rule that allows the ECS instance to reach the Lindorm endpoint on the required port. For instructions, see Add a security group rule.
Network type mismatch
Connection failures can also result from incompatible network configurations between the ECS instance and the Lindorm instance. Identify your scenario below.
ECS is in the classic network, Lindorm is in a VPC
Classic network instances cannot connect to virtual private cloud (VPC) instances.
ECS and Lindorm are in the same VPC but on different vSwitches
Instances in the same VPC but on different vSwitches can communicate after you:
Add a security group rule to allow traffic between the instances. See Add a security group rule.
Configure a network access control list (ACL) to permit the traffic. See Add rules to the network ACL.
ECS and Lindorm are in different VPCs
Instances in separate VPCs cannot communicate by default. Use Express Connect to establish connectivity between the two VPCs. For guidance on choosing the right VPC connectivity solution, see How do I choose a proper VPC solution.
ECS is on a non-Alibaba Cloud network
If the ECS instance connects to Lindorm over a network not hosted on Alibaba Cloud (for example, a corporate internal network), you have two options:
Enable internet access for the Lindorm instance and connect over the public internet.
Use an Express Connect circuit to extend your on-premises network to Alibaba Cloud.
Get support
If none of the above solutions resolve the issue, submit a ticket to contact Alibaba Cloud technical support.