after much trying it seems let's encrypt has something wrong in their
files.devuan.org database entry, or so. but we can't wait for their
ticket to be processed (will it ever? they are all volunteers...)

on the long term, we are working on a sponsorship by Gandi, where
HEllekin has good friends who understand and like Devuan, plus we are
old time customers at dyne.org. The sponsorship may include first
class SSL certificates.

however we cannot do anything else right now but use another domain or
create a startssl certificate for files.devuan.org

we are trying to setup files.dev-one.org to see how it goes, since
we have control on that dns and can act independently

then we'll also startssl on files.devuan.org

ciao