We are using Craft2, and want to move the assets to Amazon AWS S3.
We have two instances of Craft2, one on AWS, and one on a onprem server.
The bucket is made (and is on eu-west-1) and the IAM user got the right permissions, and the secret and key is also right.
The instance on AWS works fine and no problem to list buckets from S3, but the onprem server, when pressing the "refresh" button on bucket the spinner just spins and then gets timed out and a 500 error.
The command is: index.php/admin/actions/assetSources/getS3Buckets
Since it worked on 1 instance and not the other, I think it might be a firewall issue. Which port and IP / URI need to be opened in the firewall for it to work ?