Wi-Fi Through Captive Portal Does Not Connect

I have a Macbook Pro running Mac OS X 10.10.2. My university uses a captive portal to connect via Wi-Fi.

I was able to connect and log in just fine, but after I updated from 10.10.1 to 10.10.2, I can connect and get a valid IP but I cannot access the log in page through the captive portal. When I try to display the log in page from the browser (I have tried Safari, Firefox and Chrome) the result is the same. I get the server not found error on the browsers and the website couldn't be loaded error on the captive portal. Below is a screenshot of the error.

I am able to connect and login to the network using my iPhone and I can connect to other networks from my Mac.

I have found a couple of fixes about certificates but they did not work. Manually deleting the network configuration files and resetting DNS did not work either.

I hope there is a way to fix this.

Thanks in advance.