One of my clients reported an issue – they were seeing “Waiting for 188.8.131.52” and a blank screen when they tried to access the Apex web site I’d built for them. They were using Mozilla on a Windows PC, connecting via Vodaphone 3G – the problem was consistent, and it went away when they used their ADSL connection.
My initial response was “don’t use Vodaphone 3G” because the problem seemed to be outside of my area. It appears to be a common issue, something that some mobile operators do to reduce image sizes – c.f. https://support.mozilla.org/en-US/questions/791180 and http://www.geekstogo.com/forum/topic/277895-suspected-issue-waiting-for-1234-in-firefox-on-at/
After reading that I said I’d give it another go and see what could be done. As far as I could see, the only really viable solution is to add the “Cache-Control: no-transform” header to the responses. Since I’m using Apache, to do this I added the following to my apache config as per http://httpd.apache.org/docs/current/mod/mod_headers.html:
Header merge Cache-Control no-transform