Still nothing. I'll still keep trying anything anybody wants to suggest, but I will open up a bug for this over at Bugzilla.
I think there is no need to open a bug as the issue is at your site. I can download the RPM from said server without problems. How is your system connected to the internet? Are there any routers or proxies in the chain between the internet and your machine?
Did you test the internet connection from your server? Can you confirm it can access the internet without problems?
Did you already try yum clean all and retried installing afterwards?