This issue happens on the stage-green/blue-mirror VMs in AWS.
Problem
Whenever there is a new deployment of services to the stage-mirror VMs in AWS, a container usually takes up the IP range of the tis-preprod DB therefore blocking other containers from connecting to the DB.
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Network details can be found at the end of the inspect command. If the gateway has the address 172.21.x.x then you have found the culprit (ignore the IPs on the below screenshot)
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3. go to the directory of the container - /data/docker/stacks/<container_directory>
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