MQTT subscribing on AWS

The AWS broker does not guarantee delivering messages in sequential order. As a result, we've found that one may receive setpoints or control commands out of order and we therefore recommend against using it for any other purpose than data egress.

The order of data is often less relevant when feeding a cloud-side data store, which is a common use case for the AWS broker, but in context of SCADA it may have severe consequences if data arrives out of order and the SCADA isn't explicity filtering for that.

There are a lot of good broker alternatives out there and several deploy to AWS if that is your preferred hosting option.