EC2 Instance type results in reachability failure

Question

I have a r5.24xlarge instance with Windows 2016 + SQL Server 2017. All working good. Shut it down, changed instance type to x2iedn.8xlarge, started instance and now cannot reach instance. Instance status check shows "Instance reachability check failed". System status check passed. Instance screenshot shows Windows logon screen...

What could be wrong? How do I troubleshoot this?

Answer

Hi There

Please take a look at [this troubleshooting article](https://aws.amazon.com/premiumsupport/knowledge-center/ec2-windows-unreachable-after-driver-upgrade/) that talks about issues when upgrading drivers or changing instance types.

Here is [documentation](https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ec2-instance-resize.html#resize-ebs-backed-instance-considerations) about the compatibility of different instance types and AMI's.

Since the instance screenshot shows the Windows logon screen, it sounds like the network card is not coming up.  You can try switching back to the R5 instance type and follow steps 1, 2, and 3 from [this guide](https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/migrating-latest-types.html#upgrade-pv) to update all of the required drivers, and then try switching instance types again.

Answer

Failure to check the status of an instance indicates that the instance may have the following problems

Network or startup configuration problems
Exhausted memory
File system problems
Operating system startup failure
Volumes not mounted properly
Incompatible drivers
Exhausted CPU
https://aws.amazon.com/jp/premiumsupport/knowledge-center/ec2-windows-instance-status-check-fail/

Troubleshooting for EC2 Windows instances can be found below.

https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/troubleshooting-windows-instances.html

EC2 Instance type results in reachability failure

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