what can i say, i’m special…
For current and future people interested in this topic, it seems that on some network connections (like mobile 4G) there are issues while downloading zchunk files, at least using librepo, dnf, libdnf, packagekit and so on (I’m not sure what is the actual component involved).
While dnf respect the
zchunk=False option specified in the
dnf.conf file (in other word, dnf will download the gz or xz version of repodata files), packagekit (and/or the underlying libraries/modules) continue to download the zchunk compressed repository metadata (or the like).
Just to track this issue, these are the relevant discussions on bugzilla: