Using OPNSense router with SFR FTTH (Box 7)

[harg]

I've just have SFR FTTP installed (France) and I've been supplied with a pretty nasty "Box 7" (Appears to be an Altice GR140CG) where the fibre connection goes straight into it and it provide wifi and routing etc.

I'd like to use an OPNSense router instead and I've had a poke around the admin UI and there's nothing in there regarding a "bridge mode". (some screenshots attached)

I've read a few forum posts on the SFR community site saying to use a DMZ. Does this approach suffer from the double-NAT problem? Can anyone point me to some guidance on how to configure this? Is there a better way?

Any guidance appreciated

[Maurice]

You should be able to replace the box with a GPON ONT of your choice.

Cheers
Maurice