Repository verification exception while using S3 repo

Hi All,

I am trying to use s3 plugin for backup and restore, please find the details below

  1. I have create IBM COS bucket which is s3 compatible and created access and secret key
  2. I have added s3.client.default.endpoint to IBM S3 bucket endpoint in Elasticsearch.yaml
  3. i have added
    s3.client.default.access_key
    s3.client.default.secret_key

but while verifying the bucket, i am getting following issue

The AWS Access Key ID you provided does not exist in our records. (Service: Amazon S3; Status Code: 403; Error Code: InvalidAccessKeyId; S3 Extended Request ID: null)"

Can someone please suggest, what might be going wrong here?
Am i missing on something or IBM COS is not supported with S3 plugin?

JFYI - the ES is 3 node cluster hosted on k8s

Thanks
Pallavi C