AWS CLI and ECS query - HTTPSConnectionPool 443 error; Max retries exceeded; nodename nor servname provided, or not known

Any ideas? Have found some suggestions that this error message might be to do with region but as you can see the region is set in my config, and if I add the option '--region eu-west-1' to the cli I still receive the same error.

$ aws --version

> aws-cli/1.7.5 Python/2.7.9 Darwin/14.0.0

$ aws configure list

  Name                    Value             Type    Location
  ----                    -----             ----    --------
  profile                <not set>             None    None
  access_key     ******************** shared-credentials-file
  secret_key     ******************** shared-credentials-file
  region                eu-west-1      config-file    ~/.aws/config

$ aws ecs list-clusters

> HTTPSConnectionPool(host='ecs.eu-west-1.amazonaws.com', port=443): Max retries exceeded with url: / (Caused by : [Errno 8] nodename nor servname provided, or not known)