Wifi Analyzer will show the signal as coming from 30+ meters away when it is only about 4m (with multiple walls and floors in between)
I really wish insulation makers would use a different backing material - the supposed reflectivity of the foil doesn't really add much to the insulation properties anyway.
Can you elaborate on that? Seems hard to believe. There are many kinds of insulation without foil, and the foil backed variants tend to be more expensive. It's hard to imagine that we'd be making the stuff like that without a good reason.
One could use a plastic film instead though, or even corrugated cardboard.
The effectiveness of the film for insulation depends on many things.
Energy is lost through radiation, conduction and convection. At every layer of a house wall, the contribution of those effects varies widely.
Within the panel, radiation has near zero impact, because the foam material is directly in contact with the foil.
Outside the panel, the foil might have a benefit. The benefit would be maximized if there was a multi-millimeter air gap, followed by a very hot surface (Radiation doesn't scale linearly with temperature).
The foil also has a downside for insulatitive properties... The aluminium the foil is made out of conducts heat very well. That means if part of the wall is leaking some heat (for example has a nail through it), then the foil will spread that head sideways through the wall, increasing overall losses, sometimes dramatically.
The house is detached, very open plan, and doesn't have many solid walls. We also have traditional wall radiators, I imagine the lack of underfloor heating and foil insulations allows wifi to travel further between floors.