Open the configuration page of the HomeBox, with luck you just have to enter the VoIP PIN.

If not you have to call the hotline.

Thank you for the quick response. Sorry I’m not very good at these things

What would be the home box configuration page & what is the VoIP Pin?

Short instruction https://www.o2online.de/assets/blobs/pdfs/kurzanleitung-o2-homebox-6441-englisch/

Open an Internet browser via the device connected to the HomeBox and go to o2.box or 192.168.1.1 .

The VoIP PIN is a 4 digit number you could find in Mein O2 or in the willkommen letter.

Thank you again, I really appreciate. 
it says the pin is registered fine, but on this screen summary there are some red flags. Online status? Is this an issue?

Call the hotline… No Internet connection. Please do not talk from WFi!