Presigned URL with custom hostname not working

I am following this to generate a presigned URL for download:

https://docs.digitalocean.com/products/spaces/reference/s3-sdk-examples/#generate-a-pre-signed-url-to-download-a-private-file

It does work as I receive a URL, but it has the DO domain. The format is like this: <region>.digitaloceanspaces.com/<space-name><filename><tokens>

According to the above mentioned Documentation, I can also use my custom (sub)domain.

…then modify the hostname in the URL to be the CDN hostname (<space-name>.<region>.cdn.digitaloceanspaces.com, unless the Space uses a custom hostname).

But If I change the URL to this: “MySubodmain.MyDomain.com/<filename><tokens>” it will throw a “SignatureDoesNotMatch”.

I do have the CNAME on my subdomain correctly setup as I can view non-signed urls without any problem.

As a sidenode: Besides above, the format that the Signed URL comes back is NOT as mentioned in the documentation. The Documention says this: <space-name>.<region>.cdn.digitaloceanspaces.com But it comes like this <region>.digitaloceanspaces.com/<space-name>