Cannot open console to running instance

Issue

• Cannot open console to running instance

• When opening console, at URL like:
  https://servera.example:xxxx/vnc_auto.html?token=xx.xxx
  return error page with content (in Firefox):

The connection to the server was reset while the page was loading.
The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.