Yes, thanks, Mix, wifi and ferroconcrete do make an interesting match, and yes, I have done a full survey of the building with a pad; rather surprising readings sometimes.
No, the setting up was done in the same room as the wireless router - signal there was aplenty, communication ideosyncratic.
I just hope that the settings I've saved will work if some idiot presses the reset button. (I know: why should they - but how do some of these idiots remember to keep breathing?)