IPv4 only and IPv4/v6 for Multi-WAN

Router
1

Hi

On the MT3000, I can connect via phone tethering and repeater Wi-Fi at the same time, giving me two WAN interfaces. However, most Wi-Fi networks I connect to only support IPv4, which causes all IPv6 traffic to route through the tethered phone and drain my cellular data. I use local services (eg file sharing) that use IPv6 so I cannot disable it. Is there a way to configure the firmware to isolate WAN interfaces and automatically failover/switch if the active one loses internet connectivity? If not, could a feature like this be added?

(Firmware v4.9.1-op25 beta3)

3

Hi,

At present, the firmware does not provide a built-in option to make the IPv6 Internet route automatically follow the active IPv4 Multi-WAN interface.
We have recorded this requirement and submitted it for further evaluation.

As a workaround, you can disable public IPv6 on the Tethering interface while retaining local ULA IPv6 on the LAN.
With this configuration:

  • IPv4 will continue to use the Repeater while it is available.
  • If the Repeater becomes unavailable, IPv4 will automatically fail over to Tethering.
  • Local IPv6 communication, such as LAN file sharing, will remain available.
  • Public IPv6 traffic will not use the phone connection while it is acting as the backup interface.

Configuration Steps

  1. NETWORK → IPv6, enable IPv6.
  2. Then connect to the router through SSH and run:
uci set network.tethering.ipv6='0'

uci -q delete network.lan.ip6class
uci add_list network.lan.ip6class='local'
uci set network.lan.ip6assign='64'

uci commit network
/etc/init.d/network restart

Impact and Limitations
After applying the configuration, the Multi-WAN page may show a warning that Tethering cannot access the Internet using IPv6. This warning is expected because IPv6 has been intentionally disabled on the Tethering interface.

When the Repeater becomes unavailable, Tethering will provide IPv4 Internet access only, while public IPv6 will remain unavailable.
Local ULA IPv6 communication within the LAN will remain available.

How to Restore the Original Configuration
Reconnect through SSH and run:

uci set network.tethering.ipv6='1'
uci -q delete network.lan.ip6class

uci commit network
/etc/init.d/network restart

After the network restarts, open NETWORK → IPv6, disable IPv6, apply the change, and then enable it again. This allows the router to regenerate its standard IPv6 configuration.

Thank you for your understanding and support.

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