Aws iam auth is failing to verify the EC2 region (ap-southeast-1)

Vault login with AWS auth in EC2 fails with

Error authenticating: Error making API request.

URL: PUT https://***************/v1/auth/aws/login
Code: 400. Errors:

* failed to verify i-********* as a valid EC2 instance in region ap-southeast-1

I have verified, Vault and EC2 are in same region, i.e. ap-southeast-1

---                               -----
allow_instance_migration          false
auth_type                         iam
bound_account_id                  [<account_id>]
bound_ami_id                      []
bound_ec2_instance_id             <nil>
bound_iam_instance_profile_arn    []
bound_iam_principal_arn           []
bound_iam_principal_id            []
bound_iam_role_arn                [arn:aws:iam::<account_id>:role/doorman_role]
bound_region                      []
bound_subnet_id                   []
bound_vpc_id                      []
disallow_reauthentication         false
inferred_aws_region               ap-southeast-1
inferred_entity_type              ec2_instance
resolve_aws_unique_ids            true
role_id                           *******************strong text**
role_tag                          n/a
token_bound_cidrs                 []
token_explicit_max_ttl            0s
token_max_ttl                     240h
token_no_default_policy           false
token_num_uses                    0
token_period                      0s
token_policies                    [doorman]
token_ttl                         24h
token_type                        default ```