My problem starting in were initialy solved by the tweet above, which worked as advertized. Windows users please notice hosts file is in %systemroot%\System32\drivers\etc (usually C:\Windows\System32\drivers\etc).
An additional issue I am having is numerous instances of the Security Alert saying “The Internet site you are about to view uses a certificate that has expired or is not yet valid. Do you wish to proceed?”. This message is self-descriptive. It takes a good number of clicking “Yes” for the alerts to go away things to finally work.
Mixero client is now connected again 🙂