The error message simply means that something is failing to connect properly somewhere along the line (which doesn't directly help you very much!).
However, after reading your post at 1018, I recalled that I had a similar problem where I couldn't access a particular website from any device connected to my router at home; it turned out that the DNS server used by my ISP was blocking it. (It wasn't a 'questionable' website, such as one filled with porn or terrorist material; it was simply the website of the Sheffield Star newspaper, so I've no idea why access to it was blocked!).
The fact that your friend can access the site, but you can't, strongly suggests to me that your ISP's DNS server is similarly blocking access to the site you wish to visit so, as I wrote above, you need to change the DNS server used by your router (or by your individual devices).
Rather than going into your router settings (which can be a bit daunting for the uninitiated) I suggest configuring your PC to use OpenDNS (or another free DNS server, such as Dyn) by following the instructions in my first link above. If that works, you can then either try to change your router's DNS settings or, probably simpler, change them for for iPad separately. (Whichever way you do it, the settings you enter will override your ISP's choice of DNS server, allowing you to bypass the block which it's imposing on your internet traffic).