self-hosting website problem =(?

about 2 weeks ago, my friend just started self-hosting for his blog (the original platform was wordpress).. but then, last week (until now) he claimed that he can't access or even display his website.. at first he thought it was the self-hosting provider problem, but it was not.. right now he only can open the site using Opera browser.. every time he use mozilla, iexplorer and chrome, it will display error message..

so, here is the conflict, al of my friends and i who use a fixed-line-modem can access his site.. in the other hand, my friends who use a mobile/portable modem (the one that uses sim card) can't even open the site..

there was a guy told him to clear all of his cookies, but it doesn't work at all..

can anyone tell me what is actually happening and what to do??..

is it something to do with the DNS, proxy or anything of the modem?

btw, can u please take a look at this blog and tell me can u open it or not, what kind of broadband are u using, and your location.. ASAP

here: http://alieff.com/