Correct answer - "The cluster name Parameter isn't reflected in the file /etc/ecs/ecs.config
during bootstrap" : In the ecs.config file you have to configure the parameter
ECS_CLUSTER=your_cluster_name to register the container instance with a cluster named
your_cluster_name
"The ECS agent Docker image must be re-built to connect to the other clusters" - Not the case
here because we know that the template is working for one cluster but its only when creating to
other clusters which lead us to look at our template
"The EC2 instance is missing IAM permissions to join the other clusters" - We know that the EC2
instances are getting registered to first cluster so permissions is not an issue here but rather
a configuration issue that needs to be looked at otherwise we would usually get an authorization
related error
"The security groups on the EC2 instance are pointing to the wrong ECS cluster" - Security group
rules specify which incoming network traffic is delivered to your container instance. This issue
is not incoming network traffic