For a while I've been unable to download most podcasts in iTunes. They are ticked in my iTunes preferences and some will work, but for most i click subscribe and the progress bar flashes up as if it's going to download for about a second, but then seems to reset and nothing downloads.

If I try to update from within my iTunes podcasts page I get an exclamation mark and an error message reading "the network connection was lost - please check the URL and try again".

I'm in China but these podcasts all worked over here in the past.

Anyone have any ideas how to diagnose or fix this?