I upgraded my virgin media hub to hub3 and now get this when trying to connect for Retail - Classic works fine
You may want to give disabling IPv6 support for “modern” WoW within its networklng menu a try, alongside making sure all the necessary ports have been enabled in the new router.
There are a few differences between the two games when it comes to routing, and it is unfortunately quite possible that your new router may not be properly supporting full v6 mode or has some port-level restrictions - sadly newer does not necessarily equate better in that regard.
You can find more detail on that particular error message by clicking here. 
Since this I had been using a wired connection which died a week ago. I then got a new wireless network card but I am still getting this error and nothing I do seems to work. I cannot get any Blizz game to work but am able to play other online games, browse internet and download stuff