A former client has approached me with the problem that their site is no longer accessible from within China. All pages return a 403 Forbidden, and the site can not be accessed through the IP address either. The IP address can be pinged though. No other sites are hosted on that IP.
They have subdomains which are hosted on servers in their office (and not by the host responsible for the main domain) and those pages are accessible.
It doesn't seem to be blocked in other countries, as they have salespeople throughout the world whom haven't complained.
They sell a CAD product, and do not have any content that would be thought to be seditious.
Roughly two weeks before they started being blocked, I helped them launch a site redesign. None of the content changed, but the layout did extensively. It also has a Business Edition Google Site Search integrated in to the new layout.
Any thoughts? If they are being blocked, what avenues should be explored to rectify the situation? Are there any ways to deal with it from within the Chinese authority?