Summary of issue:
RbDev has created an S3 bucket with S3FullAccess policy and a IAM role to give read/write permissions.
They configured S3, saved all changes, and clicked the “Test button” and it returned successful.
When he tried to upload a file, he got an error “there appears to be a problem with your internet connection.”, but going to the s3 repo he could see that the file is there. There are no log errors and the issue happens all the time. https://mattermost.atlassian.net/browse/MM-10677 is not related.