Continuing my stream of thoughts on networks and communication in Shanghai I noticed that even with Opera Mini I could not access Facebook service despite the browser tunneling all traffic in an encrypted form to a gateway. A closer look revealed that OperaMini when used over Wi-Fi on my phone selected a gateway in China which explains this behavior.
Then I thought let's deacivate Wi-Fi, restart the phone and try again over cellular. In this setup, the GGSN is in my home country so I am assigned a German IP address and DNS server. As a result, Opera Mini should then connect to a European gateway. But strangely enough that was not the case. Despite the German IP address used for my phone (which I verified), it was still a Chinese gateway that was used!? Not only could I still not access that social networking site but each IP packet traversed from Shanghai to Germany back to the Chinese gateway and then back to Europe or the US to other websites. And the incurred delay and the websites not accessible are quite noticeable.
Very interesting! Do you know technically how this filtering of roaming traffic happens?
What network were you on?
I was in China a few weeks ago and had a prepaid card from Unicom. Lots of things did not work, or worked very slowly. Gmail were not available in certain cities. Google maps took for ever etc etc.
I did test the Opera mobile as well, and had similar experience as you.
Strange thing was that when I activated a VPN server, it was all working OK.
So they must be doing lots of things in their network..