Modem + ISP Router + OPNSense Configuration suggestions (edited)

[otherego]

Hello,
i'm using opnsense behind a 7530 Fritzbox router that is connect to ZTE moden by pppoe.
my actual provider (aruba italy) gives me static ipv4 and ipv6 addresses.
What is best configuration for opnsense, i have any trouble with ipv4, but i was wondering what is best configuration for ipv6 part.
Also i would like to know if actual configuration is correct by placing opnsense behind the router or if is better to put in front of it

Thanks