OK we have been seeing reports of this problem but never enough data
to pin down what of many problems it could be. Patrick Uiterwijk has
written a script which if people could check and run it will help us
greatly. The code is at https://github.com/puiterwijk/check_metalink
and looks to require the python-request-ftp module which isn't in EPEL
but is in Fedora 21->22 [This is mainly to check ftp hosts.. if you
only care about http.. don't worry]