Connecting OpenWRT router to NTT-Docomo IPoE ONU

Hello everyone,

I’m a Japan-NTT user and new to OpenWrt (though I'm somewhat comfortable with Linux, but I don't have much experience with networking). I recently purchased a 10Gbps plan from NTT-Docomo-Hikari, with OCN as my ISP.

THE PROBLEM: I cannot get a public IPv6 address delegated from OCN. No internet via the ONU. The router currently has internet via a temporary WiFi client (wwan) used for setup only.

A subcontractor from Docomo came to install the ONU and confirmed everything was working fine. However, I couldn't test the internet at the time, so I'm taking their word for it. I then flashed my GL.iNet Flint 2 GL-MT6000-JP router with OpenWrt (v25.12.2) via the sysupgrade image, and connected the ONU to the WAN port of my router, but I couldn’t get internet connectivity.

I called the ISP, and they explained that the ONU only supports IPoE (MAP-E, not MAP-T), which is IPv4 encapsulated inside IPv6 (or is it the other way around?), and does not support PPPoE. I attempted to follow this guide by fakemanhk (link; the full guide is on GitHub), but I couldn't obtain a global IPv6 address, let alone IPv4 connectivity.

I’m unsure whether my ISP supports SLAAC or DHCPv6. Should I call them to clarify this?

They weren’t able to assist with my GL.iNet Flint 2, but suggested that if I had purchased a recommended router (e.g., TP-Link Archer BE7200), I would simply need to enable “virtual connect” to connect to the ONU, and my router would be assigned a global IPv6 address. I’ve ordered this router and plan to test it once it arrives (<1 week).

Here are the steps I followed of the guide linked above.

  1. $ apk add map
  2. Go to web interface -> Network -> Interfaces -> wan6 (Edit) -> DHCP Server -> Set up DHCP Server.
  3. General Setup; Unchecked "Ignore interface" (this wasn't explicitly mentioned in the guide).
  4. IPv6 Settings: Designated master (tick); RA-Service: relay mode; DHCPv6-Service: relay mode; NDP-Proxy: relay mode; Learn routes (tick).
  5. Under Interfaces->WAN6->Firewall Settings: wan (empty)/wan6( empty)/wwan
  6. At this stage, the guide says I should be getting a public IPv6 address from the ONU. I'm not getting one.
  7. The guide also said:

Enable WAN6 with DHCPv6, firewall setting you probably need to add this to WAN Zone (same as IPv4 WAN) for protection.

Not sure I fully understand what they meant by this. I haven't checked the "Disable" box for WAN6, and I unchecked "ignore interface" as mentioned in (3). Am I supposed to do anything more?

Here are the changes from 2-5 in terms of uci commands:

uci set dhcp.wan6=dhcp
uci set dhcp.wan6.interface='wan6'
uci set dhcp.wan6.ignore='1'
uci del dhcp.wan6.ignore
uci set dhcp.wan6.master='1'
uci set dhcp.wan6.ra='relay'
uci set dhcp.wan6.dhcpv6='relay'
uci set dhcp.wan6.ndp='relay'
# /etc/config/network
uci set network.wan6.reqaddress='try'
uci set network.wan6.reqprefix='auto'
uci set network.wan6.norelease='1'
uci set network.wan6.multipath='off'

When I connect the router to the ONU now, my WAN6 interface is still red.
Protocol: DHCPv6 client
Carrier: Present
MAC: (I've redacted this)
RX: 774 B (9 Pkts.)
TX: 180.26 KB (531 Pkts.)

Happy to provide any more details.

EDIT#1: better phrasing
EDIT#2: RX/TX correction.
EDIT#3&4: clarification

Don't become irritated by this.
The colors of the interface doesn't indicate "work/doesn't work" but zones.
So this is as it should be.
Green is the LAN zone, red is the WAN zone.

Update: The TP-Link Archer BE7200 router came (recommended by OCN), and it works fine (as expected). i.e., the ONU was properly set up. Unfortunately this means that the OpenWrt router must take a backseat as a repeater/access point, for this now remains an academic curiosity. Nevertheless, if anyone has ideas they want me to try, e.g. to replicate the success they have had, I'm more than happy to keep trying on this. Possibly may be helpful for others that are facing a similar issue.
Thanks.