Trisque 9 update issue

Today, when I did "sudo apt update", it said there were 9 packages that could be updated, so I did "sudo apt upgrade". To the usual question whether I want to continue, I press enter (yes by default) then I had one error message per repository to check saying that fr.archive.trisquel.info can't be resolved. I retried once, same outcome. I tried to ping fr.archive.trisquel.info, there was a message saying it can't be resolved. In order to get some trace in English to report here, I did "LC_ALL=C sudo apt upgrade" and then the upgrade worked. I checked, ping still gave the same result about fr.archive.trisquel.info, it could not be resolved (I tried in the same terminal, so same environment exactly).

Does apt select the mirror based on the locale?

With respect to fr.archive.trisquel.info (with dig, I see it is an alias to es.archive.trisquel.org), the error by far does not occur at every update, but I already had it a number of times. I am running nscd following the advice from Guix.

Is it a problem with the DNS server that handles fr.archive.trisquel.info? Or is it a local issue on my computer?