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Flet'HFlet'H Docs

Troubleshooting

This documentation is still being edited and may differ from the actual version.

wan6 has no IPv6

Section titled “wan6 has no IPv6”

Do not start by changing Flet’H settings. IPv4 over IPv6 requires a working IPv6 connection.

Check:

  • Whether the ONU is working.
  • Whether DHCPv6 is enabled on OpenWrt wan6.
  • Whether the upstream interface is correct.
  • On OpenWrt 25.12, try clearing Default DUID.

Provider detection fails

Section titled “Provider detection fails”

Common causes:

  • The current network is not the expected ISP line.
  • IPv6 DNS resolution is not working.
  • The upstream IPv6 address or prefix is not available yet.
  • The ISP service was just activated and is not ready on their side.

Restart wan6, then apply the Flet'H IPoE interface again.

MAP-E works, but some ports do not

Section titled “MAP-E works, but some ports do not”

MAP-E does not provide a full unrestricted public IPv4 address. You can only use the port ranges assigned by your ISP.

Check the available port ranges in Network -> Flet'H, and avoid forwarding ports outside those ranges.

IPIP6H appears connected, but communication fails

Section titled “IPIP6H appears connected, but communication fails”

Check Network -> Interfaces -> Flet'H Static IP -> Edit -> Firewall Settings.

The Flet'H Static IP (IPIP6H) interface must have no firewall zone assigned. Do not place it in any zone, especially the wan zone, because conflicting firewall rules will prevent communication. Remove it from every zone, save and apply, then restart the interface.

Do not change the wrong interface: the upstream wan6 interface should remain in the wan zone.

LAN-side IPv6 does not work

Section titled “LAN-side IPv6 does not work”

The most common cause is firewall configuration:

  1. Check Firewall Zones: Ensure Network -> Interfaces -> wan6 is correctly assigned to the wan zone (usually red) in the firewall settings. If it’s unspecified, communication will fail.
  2. Enable IPv6 Forwarding: In Network -> Firewall -> General Settings, ensure IPv6 Forwarding is set to accept.
  3. Client Behavior: Android devices do not support DHCPv6 and rely on RA. Please double-check that SLAAC or PD is correctly selected in LAN IPv6 設定.
  4. Connectivity Test: Run ping6 2001:4860:4860::8888 (Google Public DNS) from a client terminal. This helps determine if the issue is DNS resolution or the routing path.

Configuration changes do not take effect

Section titled “Configuration changes do not take effect”

Try these steps in order:

  1. Save and apply the LuCI configuration.
  2. Restart the Flet’H-related interface.
  3. Restart wan6.
  4. Reboot the router if needed.

If the problem remains, collect this information before asking for help:

  • OpenWrt version.
  • Router model.
  • ISP name and service name.
  • Whether wan6 has an IPv6 address or prefix.
  • Detection results shown on the Flet’H information page.