Just in case it helps any of you guys, Google Chrome is working on my Mac.
But nothing else. If you need to get on the net with a browser Chrome should work for you too. There is a delay when opening web pages, but I think it is trying to use the Apple DNS service, giving up and then using it's own.
It looks like the update has broken the DNS service that resolves IP addresses. In console.app there are lots of error codes whenever you attempt a DNS operation.
Oddly in terminal you can resolve IP adresses using 'nslookup' but not using 'ping'.
I even installed Sierra on top of itself but to no avail. I think we will just have to wait until they fix this.
I'm flipping glad I didn't install it on my main machine so at least I can run libraries locally until they fix it.