Some of the mirrors also declare HTTPS access, and in that case the service is offered in their nominal domain names and not in the doman name "deb.devuan.org". This is because HTTPS access requires the service to have a certificate for the service domain, essentially proving that they are the current renter of the domain name. That's what the S part of the HTTPS service means.

To have deb.devuan.org resolve to some particular service IP addresses other than the authoritative name resolution, you need to arrange for that in your client; e.g. by populating your /etc/hosts file, or set up your own DNS service.

But they didn't work. Throw me some errors about how that mirror didn't have a release file. I checked them in the browser, I point them just exactly like the default apt devuan mirror is.