You opened 3 tickets. 1 of them was already replied to yesterday. You also posted our update servers ip addresses here on the forums and is why I had to edit your reply previous to mine. We don't have any more ip addresses to provide for you.
Your issue may not have anything to do with the update checker as I've already explained it's an ajax call within CB > Configuration so it wouldn't be able to block configuration and would only fail the ajax call. Plugin version checking is done in CB > Plugin Management so if this was your issue that would also fail. I've already explained what your potential issue is below.
www.joomlapolis.com/forum/255-developer-members-support/239937-urgent-configuration-problem?start=6#307989