it is really looking like the network you're on is explicitly blacklisted.
if you really want to get to the bottom of it, download wireshark from
Wireshark · Go deep.
start a capture on your wired connection (it will be whatever connection has packets counting up) then attempt to go to the webpage, let it fail, wait 5 seconds, and stop the capture.
then save and post it up.
close out any other network applications and don't do anything else while you're capturing, since it will capture all network activity and you don't want to post up a capture with private IM conversations in it or anything.