Exact same issue as reported
here and
here.
It is NOT my firewall or network. I have not made any network changes.
[EDIT: I am not using proxies.]
Other than this chronic issue Avast works perfectly and consistently over years.
Everything has been working fine.
As soon as this set of definitions loaded, all DNS resolution was blocked.
Turn off shields and everything works.
Turn on shields and everything stops.
It's consistent, easily and fully reproducible, and it happens every few months with a definition update.
@Avast - you need to check for this condition in QA! It's crippling!