Current setup is a Target Group with an Auto Scaling Group providing the instances for an ELB (Application Type).
This strange behavior is happening, as soon an instance is added, it has this port 80; whereas all the containers are using dynamic mapping. Obviously this port 80 becomes unhealthy right away, sometimes it's the same instance of a healthy target, but the health check fails on an instance, and the ASG brings down the instance with the good target as well.
Target Group is set to "INSTANCE" type.