We had reports that your mirror (mirrors.nic.cz) is no longer up to
date. Usually this would not be a problem as MirrorManager is disabling
outdated mirrors, but as you are also using report_mirror which claims
that your mirror is up to date, the state of the mirror is flipping.
It seems parts (especially fedora-secondary) of your mirror are no
longer updated since 2017-04-02. Could please have a look if something
is not working correctly. Thanks for supporting Fedora with your mirror.
I have temporarily disabled your mirrors as it seems to be a problem for
some clients. You can re-enabled it yourself or let me know.
Adrian