I think quite a of us have had problems during the extremely cold conditions we have recently had.
The first problem is that the Varistream was never designed to work with micro bore hose. This was confirmed when Williamses invalidated the guarantee for the V if it was used with this small bore stuff.
The v2 measures the draw of the amps and responds, cold water being thicker will cause the V2 to shut off sooner, because the amp draw needs to be higher to pump it.
I have had to re-adjust mine a few times because as the day warmed up the water got a bit thinner, and I was getting too much pressure.
Another thing that will affect the V2 is the distance you are working from the hose reel, water runs a lot more freely through a 100 meters layed out flat, than it would through 10 meters with 90 left on the reel.
It's a total waste of time giving other people your V2 settings, as settings have to be tuned to your own system.
A surflow pump with the pressure switch bypassed as it should be, no matter if that pump was originally 60 or 100psi, will pressurise up to 130 psi with the V2 running at max. that is serious and connector damaging pressure.
I don't believe the auto compensating spiel either. it may work with 6mm I/D pole hose, but won't with 4mm I/D Algarde hose. I know this for a fact after having the pump stop when lifting the pole to do the third floor.
I have only had the pump cycle if I have had air in the system, or had a small leak somewhere, and working with too much pressure is a sure way to find leaks.