Fritz!Box 7581/7583 + Unifi USG (XS4ALL VDSL2 PPPoE with IPv6)

01 Oct 2019 - sebas

This setup puts the Fritz!Box in a bridge-like mode, allowing the USG to setup it’s own PPPoE connection. You won’t have double-NAT issues and IPv6 will work.

XS4ALL-provided phone and television service will likely not work.

FritzBox setup

Follow PE1PZU’s great guide to configure the Fritz!Box.

UniFi setup

WAN settings

Set WAN network settings (for PPPoE username/password, you can enter anything):

After setting the WAN settings to PPPoE, you must restart the USG (i.e. power cycle), otherwise it will not connect.

Now the IPv4 connection will work, but I had to add the following to config.gateway.json to get IPv6 to work.

{
    "interfaces" : {
        "ethernet" : {
            "eth0" : {
                "pppoe" : {
                    "0" : {
                        "dhcpv6-pd" : {
                            "prefix-only": "''",
                            "pd" : {
                                "0" : {
                                    "interface" : {
                                        "eth0" : {
                                            "host-address" : "::1",
                                            "service" : "slaac"
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

After changing config.gateway.json, force-provision the USG from UniFi.

LAN settings

Now you can enable IPv6 in the LAN network. Set IPv6 Interface Type to Prefix Delegation and IPv6 Prefix ID to 0 or higher.