One would normally do this, I tried previously but did not work. But I did try again, plus this time I ran the (new sw interface on Fritz) wizard on my Fritz!box router to set-up internet over WAN connection and it worked!
I have been told just two days ago (and previously) that this modem does not support Bridge mode, so cannot take advantage of my Fritz!Box router for WiFi and DHCP etc.
I was also told that I should request that UPC (but I am with Sunrise) run the cable for a HFC connection to the house, install the connection plug then Bridge mode is available.
Finally I requested a Fritz!Box modem/router for fibre, so in fact I will not need two boxes. I can do all from my new router (Wifi, DHCP) and stay compatible with all the Fritz!Box AP’s in the house using Mesh.
But now having Bridge mode working, I might stay with what I have.
Good luck everybody!
Btw the modem is a Zyxel box