Problem solved !!!!!
The problem was that a second language (German) was made default language but it was not published.
Now the page apears, also on IOS devices.
But still,,, I am somewhat disapointed that all you experts did not know what I was talking about. Also still, nobody can explain why this problem ony ocurred on IOS devices and not on a locak desktop PC, wit most of the existing browers, except MS edge.
So there seems to be a lot to learne for both of us. I am still dealing with Joomla a couple of weeks now, some hous a day, you do this all day for years now !!.