IPv6 with static prefix behind a router (FritzBox)

[Perun]

Hi all,

I have received a static IPv4 and a static IPv6 prefix from my internet provider. IPv4 is clear so far. I have a few questions about IPv6.

My setup:
ISP -> Fritzbox -> OPNsense -> LAN
Fritzbox and OPNsense are together in a DMZ (IPv4). The Fritzbox forwards everything to OPNsense (exposed host).

Is such a setup also possible with IPv6? I tried to create a /64 IPv6 DMZ network with the prefix from the ISP. OPNsense has an IPv6 address there, and I specified the fe80:: address of the Fritzbox as the gateway. I would prefer to avoid RA/DHCPv6 etc. and have everything static. Unfortunately, with this setup, I can only ping the fe80:: address of the Fritzbox from OPNsense but nothing in internet.
Am I thinking something wrong? I have some knowledge of IPv6, but I lack experience

Can someone help or recommend a how-to?

TiA
Greetz

[Perun]

aaach have it... the backroute on the Fritz was missing/wrong

now everything works as it should