Nope, no luck trying that.
As far as I can tell NAPT is for when more than one computer is connected to the router. But I could be wrong.
I think I need expert help. That's what I'm hoping for here.

I think I need to get back to the computer shop and ask if they know of problems with this model....
Or if they know how to update the firmware. The link from the router's browser settings doesn't work.