Aurora MySQL 5.7 randomly fails
Special thanks to @WilsonHauck. After 4 weeks of monitoring, Manually upgrading Aurora to the latest version solves the issue. 

There have been several bugfixes addressing unexpected restarts on 2.01.1. https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/AuroraMySQL.Updates.20Updates.html

To manually upgrade your Aurora: 


Go to RDS - AWS Console
Navigate to Clusters
Select your cluster
Click Actions >> Upgrade now