Everything has been pretty much fine since you upgraded the firmware on my Hub One back (no more 5GHz weirdness, thankfully) but twice recently the DNS issue described in the above post has reoccurred. That is, any devices on my network that weren't using non-PN DNS servers couldn't resolve anything. IP addresses could be pinged, but not domain names. The only way to resolve this was - as before - to disconnect the broadband and turn off the router for a few minutes.
This happened on 18 November at some time between 12:50 and 13:20, and today at about 14:20.