Difficult to say what happened. I asked them to try the alternate domain names, what seemed to be successful, as was the raw IP. Finally, I asked them to try again the .org domain, and they were finally able to access it! Maybe it came from the extreme set of VPN and proxies they have to use to access the “outside world”, plus the relative slowness of the network in Tehran that seems to be around 100 KB/sec. Thanks for helping anyway...