I literally did nothing, and DWC started working again. <facepalm> I tried everything yesterday to get it to work, turned off all the addons, restarted, checked network, etc etc. Today, i fire up the printer and it just works again. i dunno wtf got it to fail yesterday. And I can't get it to reproduce again today. I'll put it down to weirdness with firefox i guess.
Thanks for the advice. I'll be done with this project soon and i'll suck it up and upgrade my firmware.