Goodmorning @Cargento and a warm welcome to our Community,
I am very sorry that you're currently unable to use the advanced router functions from the SmartWifi (Connectbox) modem. It's good that you contact us via this topic for assist. I took a quick look at your connection and I see that the modem has an IPV6 DS Lite address. As a result, the advanced router features, including Port Forwarding, do not work at this time. To solve this problem, I have submitted a request to change your modem profile to IPV4 only. It must then be possible to use Port Forwarding within 24 hours at the latest. In some cases a modemreboot is required. You only need to do this if it doesn't work after 24 hours have passed.