Aaaand it came back by itself.  I've noticed on the odd occasion DNS seems to stop working over the last couple of weeks or so

Don't know how long you've been with Orcon, DNS servers do come and go seemingly randomly...

I've resorted to using GRC's DNS benchmark tool

https://www.grc.com/dns/benchmark.htm

And just kept the list handy... for whenever Orcon's DNS craps out. Not pretty but kinda works...