Hi @Ex-Community Member,
The Connect box will be only used as a modem (Internet + Phone) and the Horizon box will be only used for the TV.
The boxes don’t have to be connected to each other but have to be connected to the 3-1 cable connection (see the 1st picture below). If you have only one 3-1 cable connection in your home, you can ask the hotline for a splitter (see the 2nd picture below). Make sure you have a 3-1 cable connnection with three hole. If you have one with 2 hole, it will be a bit different.
As you want to connect your Asus router to the Connect Box, you have to say to the hotline that you want switch from IPv6 to IPv4 which will allow you to use brigde mode.
More infos about bridge mode with the Connect Box and how to configure it (page 26) : http://www.upc-cablecom.ch/content/dam/www-upc-cablecom-ch/Support/manuals/en/int/Manual%20Wlan%20Connect%20Box%20Modem_1115_EN.PDF
If you need more help or better explanations, I’m here until 11pm. today and tomorrow from 1pm. 😉