I have " Instance reachability check failed". How can i solve this problem? There is logs.

Question

Hello guys.

I cannot SSH into my instance. The status check shows a message saying "Instance reachability check failed."

At first, I thought it was a memory issue, so I changed the instance type, but the error is not resolved.

In the monitoring log, I can find a few failed messages.
"mGRUB failed boot detection"
"Failed to start Service for snap application lxd.activate"
"Failed to start Service for amazon-ssm-agent.amazon-ssm-agent."

This instance only has Docker installed. How can I solve this problem?

Thank you.
```
[0;32m  OK  [0m] Started [0;1;39mirqbalance daemon[0m.
         Starting [0;1;39mAuthorization Manager[0m...
         Starting [0;1;39mSystem Logging Service[0m...
         Starting [0;1;39mLogin Service[0m...
         Starting [0;1;39mDisk Manager[0m...
[[0;32m  OK  [0m] Finished [0;1;39mRecord successful boot for GRUB[0m.
         Starting [0;1;39mGRUB **failed** boot detection[0m...
[[0;32m  OK  [0m] Started [0;1;39mSystem Logging Service[0m.
[[0;32m  OK  [0m] Finished [0;1;39mGRUB **failed** boot detection[0m.
[[0;32m  OK  [0m] Started [0;1;39mNetwork Name Resolution[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mNetwork[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mNetwork is Online[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mHost and Network Name Lookups[0m.
         Starting [0;1;39mcontainerd container runtime[0m...
         Starting [0;1;39mEC2 Instance Connect Host Key Harvesting[0m...
[[0;32m  OK  [0m] Reached target [0;1;39mRemote File Systems (Pre)[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mRemote File Systems[0m.
         Starting [0;1;39mLSB: automatic crash report generation[0m...
         Starting [0;1;39mDeferred execution scheduler[0m...
         Starting [0;1;39mAvailability of block devices[0m...
[[0;32m  OK  [0m] Started [0;1;39mRegular background program processing daemon[0m.
[[0;32m  OK  [0m] Started [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
         Starting [0;1;39mService for snap application lxd.activate[0m...
         Starting [0;1;39mPermit User Sessions[0m...
[[0;32m  OK  [0m] Started [0;1;39mLSB: automatic crash report generation[0m.
[[0;32m  OK  [0m] Finished [0;1;39mAvailability of block devices[0m.
[[0;32m  OK  [0m] Finished [0;1;39mRemove Stale Onliâ¦ext4 Metadata Check Snapshots[0m.
[[0;32m  OK  [0m] Started [0;1;39mDeferred execution scheduler[0m.
[[0;1;31mFAILED[0m] **Failed** to start [0;1;39mService foâ¦snap application lxd.activate[0m.
See 'systemctl status snap.lxd.activate.service' for details.
[[0;32m  OK  [0m] Started [0;1;39mAuthorization Manager[0m.
         Starting [0;1;39mModem Manager[0m...
[[0;32m  OK  [0m] Finished [0;1;39mPermit User Sessions[0m.
         Starting [0;1;39mHold until boot process finishes up[0m...
         Starting [0;1;39mTerminate Plymouth Boot Screen[0m...
[[0;32m  OK  [0m] Finished [0;1;39mHold until boot process finishes up[0m.
[[0;32m  OK  [0m] Started [0;1;39mSerial Getty on ttyS0[0m.
         Starting [0;1;39mSet console scheme[0m...
[[0;32m  OK  [0m] Finished [0;1;39mTerminate Plymouth Boot Screen[0m.
[[0;32m  OK  [0m] Finished [0;1;39mSet console scheme[0m.
[[0;32m  OK  [0m] Created slice [0;1;39msystem-getty.slice[0m.
[[0;32m  OK  [0m] Started [0;1;39mGetty on tty1[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mLogin Prompts[0m.
[[0;32m  OK  [0m] Started [0;1;39mLogin Service[0m.
[[0;32m  OK  [0m] Started [0;1;39mUnattended Upgrades Shutdown[0m.
[[0;32m  OK  [0m] Started [0;1;39mDisk Manager[0m.
[[0;32m  OK  [0m] Stopped [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Started [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Finished [0;1;39mEC2 Instance Connect Host Key Harvesting[0m.
         Starting [0;1;39mOpenBSD Secure Shell server[0m...
[[0;32m  OK  [0m] Started [0;1;39mOpenBSD Secure Shell server[0m.
[[0;32m  OK  [0m] Started [0;1;39mModem Manager[0m.
[[0;32m  OK  [0m] Stopped [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Started [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Started [0;1;39mcontainerd container runtime[0m.
         Starting [0;1;39mDocker Application Container Engine[0m...
[[0;32m  OK  [0m] Stopped [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Started [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Stopped [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Started [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;32m  OK  [0m] Stopped [0;1;39mService for snap aâ¦on-ssm-agent.amazon-ssm-agent[0m.
[[0;1;31mFAILED[0m] **Failed** to start [0;1;39mService foâ¦on-ssm-agent.amazon-ssm-agent[0m.
See 'systemctl status snap.amazon-ssm-aâ¦.amazon-ssm-agent.service' for details.
[[0;32m  OK  [0m] Started [0;1;39mDocker Application Container Engine[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mMulti-User System[0m.
[[0;32m  OK  [0m] Reached target [0;1;39mGraphical Interface[0m.
         Starting [0;1;39mUpdate UTMP about System Runlevel Changes[0m...
[[0;32m  OK  [0m] Finished [0;1;39mUpdate UTMP about System Runlevel Changes[0m.

Ubuntu 20.04.6 LTS ip-***-**-*-** ttyS0
```

Answer

Hi, most issues with ssh come from either ip routing or improper sec groups.

I would recommend to start connecting with Instance Connect by following this guidance: https://repost.aws/knowledge-center/ec2-instance-connect-troubleshooting.

That should fix potential sec group issues

Then try ssh from your laptop: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/TroubleshootingInstancesConnecting.html

I have " Instance reachability check failed". How can i solve this problem? There is logs.

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