So I have added “x1” as CNAME pointing to “name.domain.” in my Custom DNS
/admin#custom_dns
But when I go to Web (Static Web Hosting) I can not see the subdomain “x1.name.domain” there
to choose the “Directory for Files” I want to use for that particular address = x1.name.domain
I have a feeling that you’ll have to create a mail user in that new domain, as it’s existence mail users that actually trigger the domain stuff. (It could be a dummy account that never gets used.)