ssh: connect to host 18.222.193.232 port 22: Connection timed out

Question

Hello, I can't ssh to my instance for last few hours. I tried running **traceroute** it shows can't reach my instance ip after reaching to amazon network. I launched another instance with same security group and vpc, but could connect to that and traceroute was also able to reach. I associated a different ip with same vpc to this instance but that didn't work wither. What might be the reason? How can I troubleshoot this?  
  
PS: I've been using this instance for 1 month and everything was fine. No security groups, vpc, subnet settings or firewall has been changed. It just suddenly stopped working.  
  
Edited by: rofi93 on Jul 23, 2020 8:20 AM

Answer

Hello,  
  
When you do not use an Elastic IP address the public IP address of the instance can change when it is stopped.

```
You cannot manually associate or disassociate a public IP address from your instance. Instead, in certain cases, we release the public IP address from your instance, or assign it a new one:

We release your instance's public IP address when it is stopped, hibernated, or terminated. Your stopped or hibernated instance receives a new public IP address when it is started.
```

More information on it here  
- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-instance-addressing.html#concepts-public-addresses  
  
To have a fixed public IP address you would need to use an Elastic IP address.  
- https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/elastic-ip-addresses-eip.html

Answer

Hello,  
  
I cannot see an instance with the IP address of 18.222.193.232 in your account but I can see another instance that has the IP address of 18.223.90.18.  
  
This instance is failing health checks on the OS level. In this case it appears that you are getting Out of Memory errors (OOM)

```
[4387432.249467] Killed process 23851 (node) total-vm:1899156kB, anon-rss:616560kB, file-rss:0kB, shmem-rss:0kB
[4388361.208192] Out of memory: Kill process 24410 (node) score 550 or sacrifice child
```

What I would recommend here is to perform a reboot from the AWS console and this should allow you to connect to the instance.   
Once connected you review the logs within your instance and look at the application that you are running.  
  
Edited by: aws-chrisa on Jul 23, 2020 8:49 AM

Answer

Thank for your response. You're right, I just checked the instance ip right now and I see ip has been changed. How did this happen or what can cause this?

ssh: connect to host 18.222.193.232 port 22: Connection timed out

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