Instance reachability check failed after installing Docker

On Windows Server 2025 Base image, installing Docker via the command below did the trick for me:

Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/Windows-Containers/Main/helpful_tools/Install-DockerCE/install-docker-ce.ps1" -o install-docker-ce.ps1
.\install-docker-ce.ps1

Taken from: https://learn.microsoft.com/en-us/virtualization/windowscontainers/quick-start/set-up-environment?tabs=dockerce#windows-server-1

I apologize for the issue you're experiencing with your EC2 Windows Server instance after attempting to install Docker. The "Instance reachability check failed" error and the inability to connect via RDP indicate that there might be a problem with the instance's network configuration or system state. Here are some steps you can try to troubleshoot and potentially resolve the issue:

1. First, ensure that your security group rules allow RDP traffic (port 3389) to the instance.

2. Check if you can access the instance using AWS Systems Manager Session Manager, which doesn't rely on RDP. This could help you investigate the issue directly on the instance.

3. If you can't access the instance through other means, you may need to stop the instance, detach its EBS volumes, and attach them to another instance in the same Availability Zone to recover your data.

4. Once you've secured your data, you could try creating a new instance from the most recent AMI backup (if available) to see if the issue persists.

5. If the problem continues, it's possible that the Docker installation process may have altered some system settings. In this case, you might need to:

   • Update the EC2Config service to the latest version
   • Check and potentially update the Enhanced Networking (ENA) and AWS NVMe drivers
   • Verify the DNS settings on the network adapter

6. If none of these steps work, you may need to create a new instance and restore your data and configurations manually.

Remember to always back up your data and create snapshots of your EBS volumes before making significant changes to your instances. Also, consider using an Elastic IP address for your instances to maintain a consistent public IP even when stopping and starting the instance.

If you continue to face issues, it would be advisable to contact AWS Support for more detailed assistance, especially if you have critical data on the instance that you need to recover.
Sources
Troubleshoot an RDP connection on Windows Server after EC2 change | AWS re:Post
Troubleshoot Amazon EC2 Windows instance start issues - Amazon Elastic Compute Cloud
Troubleshoot issues connecting to your Amazon EC2 Windows instance - Amazon Elastic Compute Cloud
Unable to connect ec2 instance | AWS re:Post

I am also facing the exact same problem as @Mat Weber Plus, when i check the get instance screenshot in Actions>monitor & troubleshoot> get instance screenshot it shows this: