NAS backup to S3 Bucket. Region Issue

Question

I created a S3 bucket in Asia Pacific (Melbourne) ap-southeast-4.  I was not able to access this from my NAS storage which does cloud backup.  I could see the bucket but not create any folders.

I configured the NAS to do the backups.  Part of that config is selecting the bucket.  It can see the bucket, but is not able to create any folders. I checked the logs and was getting an error of - Failed to sync for the first time. HTTP_TRANSPORT_ERROR: Unknown error code: IllegalLocationConstraintException, message: The ap-southeast-4 location constraint is incompatible for the region specific endpoint this request was sent to. - that error appears all over the place in the logs.

When I create a bucket in Asia Pacific (Sydney) ap-southeast-2 there are no issues.  I can configure the backup with out any issues, including adding a new folder in the bucket.

While I am in Perth, so there isn't a lot of issue with sending my backups to Sydney region, I am curious about what the issue might be.

Answer

Hello.

Perhaps the following explanation is relevant.  
The "ap-southeast-4" region was created after 2019, so unlike the "ap-southeast-2" region, I thought that an error would occur if the region was not specified at the time of the request.  
It is unclear how the backup software sends requests to S3, but if you can set the region, it may be a good idea to set the region.  
https://docs.aws.amazon.com/AmazonS3/latest/userguide/VirtualHosting.html  
> Virtual-hosted–style requests for other Regions  
> The legacy global endpoint is also used for virtual-hosted–style requests in other supported Regions. If you create a bucket in a Region that was launched before March 20, 2019, and use the legacy global endpoint, Amazon S3 updates the DNS record to reroute the request to the correct location, which might take time. In the meantime, the default rule applies, and your virtual-hosted–style request goes to the US East (N. Virginia) Region. Amazon S3 then redirects it with an HTTP 307 Temporary Redirect to the correct Region.  
> 
> For S3 buckets in Regions launched after March 20, 2019, the DNS server doesn't route your request directly to the AWS Region where your bucket resides. It returns an HTTP 400 Bad Request error instead. For more information, see Making requests.

NAS backup to S3 Bucket. Region Issue

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