I get that screen above when accessing http://www.nait.ca from chrome, but not from firefox.
I get that screen on four different computers running Mac Yosemite and three browsers Chrome, Safari, curl
curl -k (go ahead with insecure certificates) works.
Tried rebooting the router. No change.
Additional info
* Happens in incognito windows too.
* Happens on 4 different computers with different users and extension sets.
* Happens on two different OS's
* Happens in 4 out of 5 browsers.
Does not happen when my nephew in Ottawa accesses the site using Chrome on Windows, nor Safari on iPhone.
I get the same message (in text) if I use curl.
How and why would chrome be blocked, but not firefox.
After posting this, I saw that I had answers to a question on academia.SE
I suspect the two are related. Once again, it's fine on Firefox.