This video from WLL explains how to drain the boilers on an E61 machine. Specifically, removing the "mushroom nut" folks have been referencing on this thread. See here: {video}

I think your Vario is going into "Sleep Mode". This from page 7 of the manual: "This is a programmable feature to allow the lights and display to turn off after a pre selected amount of time elapses since last grinding. Also there is the ability to "force" it to sleep mode by pressing and holding th...

We need more information. Will it restart immediately? Or do you have to wait a period of time? Possible thermo overload. Are you grinding for time? Or grinding manual when it happens? Possible timer circuit board issue. Does it sound overloaded or strained when it shuts off? Possible grind calibrat...

Breville manual recommends the following for the single/double basket: "Breville's filter baskets have been designed for 10g/18g, a larger volume than the industry standard of 7g/14g. Using less than 10g/18g may affect the espresso produced."

You don't mention how long you let your machine warm up before pulling the first shot