I am using Xfinity WiFi and had no problem getting to your site on my Android Phone. I do not have xFi - thus no Advanced Security function on my WiFi.
Please go to the following thread which I believe may be the same as your situation:
It may not solve your situation, but it appears to be worth a try.
Perhaps you can check with your friend to see if they are using xFi and Advanced Security to narrow the cause down a bit more.
Sorry I couldn't help more!