The crucial setting is the checkbox **allow other routers IPv6 prefixes**. Without that the delegated internal prefixes will
not be reachable from the Internet.
Also, not stated in above document, it is necessary to modify the **Internet - Permit Access** settings for
Also, not stated in above document, it is possible to modify the **Internet - Permit Access** settings for
the OPNsense host. Make sure to select :menuselection:`Internet --> Permit Access --> <your OPN Host> --> IPv6 Settings --> Open firewall for delegated IPv6 prefixes of this device`
in order to make your delegated internal subnets available via Internet.