EC2 Instance gets Unresponsive frequently and SSH connections fail

Question

I am using an EC2 instance (AP-South-1) inside a VPC with no inbound connections, except those routed by an ELB. The server was working fine since the creation around 2 months ago. Except that since last night, the server gets unresponsive (status check was 1/2 this morning). And now when I SSH into the instance after reboot, I lose the connection in a few minutes. This keeps happening every time I reboot and reconnect. I checked all logs on the server, everything seems to be fine there. CPUS usage is minimal too (less than 20%). I have set up alarms for CPU usage and status check, nothing gets triggered when the instance gets unresponsive.

Answer

You don't say what instance type you're using so my guidance is a little vague.

First, try using the [EC2 Serial Console](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-serial-console.html) to gain access to the instance to see why it is becoming unresponsive.

Second, if you're using a T-series instance (which runs on CPU credits) check to see if you have exhausted the CPU credit balance. If this is the case I'd suggest using Unlimited mode (which will cost extra in this case); a larger T-series instance; or a non-T-series instance (which doesn't use CPU credits).

Finally, if you are continuing to have difficulties definitely create a support case and have our team assist you.

EC2 Instance gets Unresponsive frequently and SSH connections fail

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