Hello Roberto6900
I understand your annoyance with this setup.
To my knowledge, this issue is a network topology limitation and not a fault of your H165-383 device.
For standard consumer mobile subscriptions, Sunrise does not offer a public IPv4 address on the cellular network.
Since you are probably a private customer, switching to a traditional landline connection is your best option because the connection can be changed to IPv4 there via the hotline on 0800 707 707.
If a landline is not possible, you could switch to a business mobile subscription instead, but you must expect different subscription rates and business pricing there.
For details about these corporate tariffs, you can contact the business hotline on 0800 777 222 from Monday to Friday between 08:00 and 19:00.
Cheers cosmo