Perhaps try
"path_style_access" : true
PUT _snapshot/my_s3_repository
{
"type": "s3",
"settings": {
"bucket": "my-bucket",
"endpoint" : "hostname:5500",
"protocol" : "http",
"path_style_access" : true
}
}
https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-bucket-intro.html