And then i got banned from dwarfpool.
I got same problem but before that, I had many "lowdiffucultyshare" error and then "unauthenticated".
In 9.6, the miner disconnects then reconnects when I got ""lowdiffucultyshare" error.
In 9.7, it don't disconnect then I keep having the "unauthenticated" error.
yes this is what exactly happened.
Was mining fine for hours, then i logged in to the miner and saw this.
This was the case on few machines, but not on all ?!!