AWSで「502 Bad Gateway」エラーが出てしまう

前提

半年以上AWSで運用していたサービスが突然「502 Bad Gateway」エラーになってしまいました。

インスタンスがエラー後正常に復帰したと通知があったのでそれが原因になっているとは思うのですがインスタンスのほうでは特にエラーなどは見当たらず正常に実行されているようです。

Amazon EC2 がインスタンスを自動復旧した場合何か再設定する必要があるのでしょうか？

ご教授いただけますと幸いです。

発生している問題・エラーメッセージ

Description
One of your Amazon EC2 instances associated with your AWS account in the ap-northeast-1 Region was successfully recovered after a failed System status check.

The Instance ID is listed in the 'Affected resources' tab.

* What do I need to do?
Your instance is running and reporting healthy. If you have startup procedures that aren't automated during your instance boot process, please remember that you need to log in and run them.

* Why did Amazon EC2 auto recover my instance?
Your instance was configured to automatically recover after a failed System status check. Your instance may have failed a System status check due to an underlying hardware failure or due to loss of network connectivity or power.

Please refer to https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-recover.html#auto-recovery-configuration for more information.

* How is the recovered instance different from the original instance?
The recovered instance is identical to the original instance, including the instance ID, private IP addresses, public IP address, Elastic IP addresses, attached EBS volumes and all instance metadata. The instance is rebooted as part of the automatic recovery process and the contents of the memory (RAM) are not retained.

You can learn more about Amazon EC2 Auto Recovery here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-recover.html

If you have any questions or concerns, you can contact the AWS Support Team on the community forums and via AWS Premium Support at: https://aws.amazon.com/support