Troubleshooting Intermittent Connection Loss Between AWS VPN Client and EC2 Instance in a VPC

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I have a VPC in AWS and set up the AWS VPN Client to connect to a Windows EC2 instance inside the VPC. My VPN stays in a stable connected state, but the connection to the EC2 instance is lost every minute. This issue started two days ago. I was able to fix it initially, but now the connection problem has started again. I don't know how to fix it

asked 25 days ago21 views
1 Answer
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The intermittent connection loss you're experiencing between your AWS VPN Client and the EC2 instance in your VPC could be caused by several factors. Here are some troubleshooting steps and potential solutions to address this issue:

  1. Check firewall settings: Ensure that the firewall rules on both your local machine and the EC2 instance are not blocking inbound or outbound TCP or UDP traffic on ports 443 or 1194, which are commonly used for VPN connections.

  2. Verify VPN endpoint configuration: Ask your AWS Client VPN administrator to check the following:

    • Firewall rules for the Client VPN endpoint are not blocking TCP or UDP traffic on ports 443 or 1194.
    • The configuration file contains the correct client key and certificate.
    • The Client Certificate Revocation List (CRL) is still valid and not expired.
  3. Network connectivity: Since the issue is intermittent, there might be network connectivity problems. Check for any packet loss or routing issues between your local network and AWS.

  4. DNS resolution: Ensure that DNS resolution is working correctly, as DNS issues can sometimes cause intermittent connectivity problems.

  5. EC2 instance health: Verify that the EC2 instance you're connecting to is running properly and not experiencing any performance issues.

  6. VPN client software: Make sure you're using the latest version of the AWS VPN Client, as outdated software can sometimes cause connectivity problems.

  7. Security associations: AWS VPN supports one inbound and one outbound security association at a time. If there are multiple security associations, it can cause previous connections to drop. Ensure that your VPN configuration is limited to one set of inbound and outbound security associations.

  8. Logs and diagnostics: Review the VPN client logs for specific error messages. You can also send diagnostic logs to AWS Support for further assistance:

    • Open the AWS VPN Client app
    • Choose Help, then Send Diagnostic Logs
    • Follow the prompts to send the logs and obtain a reference number
    • Contact AWS Support with this reference number for more detailed troubleshooting

If the problem persists after trying these steps, it would be best to work with your organization's network team and AWS Support to further investigate the issue, as it may be related to specific network configurations or recent changes in your AWS environment.

Sources
AWS Client VPN shows "Re-establishing connection" message intermitently | AWS re:Post
Troubleshoot connection problems with AWS VPN | AWS re:Post
Troubleshooting common AWS Client VPN problems - AWS Client VPN

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answered 25 days ago
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