Teor,
Most mobile carriers use carrier-grade NAT.
Thanks for that. But yet again, I do not have anything but a 'phone passing data via wi-fi to a computer (a Raspberry Pi in this case) so there's no router. From what you say and what I've tried Optus is having a joke and limiting what we can do with 'broadband internet'. Their parents weren't married.
I have numerous foreign VPS running mostly without drama.
Robert