Why don't you just use the closest mirror. It should increase your reliability and speed
The downloads from fedora.redhat.com usually take a lot longer and as you know are much more prone to disconnects because every tries to use them and thet get saturated. This is why we have mirrors. You should use yum
to install software.
yum install <package-name>
so in your case
yum install kernel-sourcecode
You should also use mirrors in your /etc/yum.conf file.