Before Install: Get OpenWrt Online

Before installing Flet’H, solve the practical problem first: the package must be downloadable.

Note: “フレッツクロス” does not support PPPoE, providing only IPv6 (IPoE) connections. PPPoE is generally only retained by specific legacy services such as GLBB or IIJ FiberAccess.

Flet’H configures IPv4 over IPv6, but you need to install Flet’H before it can do that. So the router or the computer you are using for setup needs a working path to fetch the package first.

1. Choose a wan6 identifier fix

Choose one of the two methods below. Usually try option A first. Use option B if wan6 needs an NGN-style DHCPv6 Client ID.

Option A: clear Default DUID

Clear Default DUID in Global network options. If that does not work, use option B.

1. Open LuCI: Network -> Interfaces.
2. Open Global network options.
3. Clear Default DUID.
4. Save and apply.
5. Restart wan6.

Option B: copy the WAN / wan6 MAC and calculate Client ID

Copy the MAC from LuCI.

Find the empty Client ID field in wan6 Advanced Settings, then enter the calculated value.

1. Open Network -> Interfaces.
2. Open the wan6 interface.
3. Copy MAC address from the interface details.

WAN / wan6 MAC address

DHCPv6 Client ID (NGN): -Copy

1. Open Network -> Interfaces -> wan6 -> Advanced Settings.
2. Put the value above into DHCPリクエスト時に送信するクライアントID.
3. Save, apply, and restart wan6.

I completed this

2. Configure wan6 and apply

Open Network -> Interfaces -> wan6, then choose a configuration based on wan6 status: ipv6-prefix means PD; no ipv6-prefix but a global ipv6-address usually means SLAAC / RA.

Case A: フレッツ 光ネクスト without ひかり電話 (SLAAC)

This is usually SLAAC / RA. It applies to "フレッツ 光ネクスト" without a "ひかり電話" contract. Configure wan6 only.

SLAAC / RA line: in Advanced Settings, do not assign a downstream prefix length to wan6.

Then open DHCP Server -> IPv6 Settings; set RA / NDP to relay to allow LAN clients to get addresses.

• Protocol: DHCPv6 client
• Request IPv6-address: try
• Request IPv6-prefix: empty
• Extend prefix: enabled
• IPv6 assignment length: empty

If LuCI shows DHCP Server / IPv6 RA Settings, set the wan6 side as follows:

• Designated master: enabled
• RA-Service: relay
• NDP-Proxy: relay
• DHCPv6-Service: disabled

Case B: フレッツ 光クロス, or line with ひかり電話 (DHCPv6-PD)

This is usually DHCPv6-PD. It applies to "フレッツ 光クロス", or to "フレッツ 光ネクスト" lines with a "ひかり電話" contract. Configure wan6 first to receive the prefix.

DHCPv6-PD line: in Advanced Settings, use 64, hint 0, and eui64.

• Protocol: DHCPv6 client
• Request IPv6-address: try
• Request IPv6-prefix: auto
• IPv6 assignment length: 64
• IPv6 suffix: eui64

Completion condition: wan6 status shows ipv6-address; PD should also show ipv6-prefix.

I completed this

3. Did you save and apply?

Check the top-right corner of LuCI. If 保存されていない変更 is still shown, the settings above have not actually been applied yet.

If unsaved changes are shown in the top-right corner, do not continue yet.

Open the unsaved changes prompt, then click 保存&適用. Wait for the apply step to finish, then check wan6 status again.

Click 保存&適用, not only 保存.

I completed this

After the steps above, the OpenWrt router itself should be able to reach package feeds over IPv6. It is expected that client devices still do not have normal connectivity yet because Flet’H has not been installed and configured.

Next, install Flet’H with LuCI installation. This path does not require SSH; add the Flet’H package feed and install the package from LuCI.

After installation, continue with the classic setup flow.