Boiler turns on and off at will?

I have a vaillant ecoTEC Plus 837 boiler that is almost 3 years old. This is controlled by a salus wifi controller (I know that these are not great). The problem is at at will, the boiler turns itself on and off. I have removed the batteries from the controller so it is having no effect. The wifi receiver LED next to the boiler shows green when the boiler is on. Could a spurious wifi signal be triggering it or, is it a fault with the boiler?

Any suggestions would be gratefully received.

Thanks