Asus ROG Rapture GT-AXE16000 - dual wan (failover : fiber + cellular box) + ipv6 (for "matter" smart devices and apple)

[doge]

Hello,

I have Fiber Internet Box (France : Freebox) : https://www.free.fr/freebox/
But fiber is broken by nice guys several times a month here.

So i added second internet box on 5g (Bouygues 5g Box) :

5G box : la puissance de la 5G en illimité et sans engagement | Bouygues Telecom | Bouygues Telecom

Avec votre box 5G, profitez de l'ultra haut débit partout chez vous en attendant la fibre !

www.bouyguestelecom.fr

I activated dual wan on my GT-AXE16000 and it works well.

I also plan to have some "matter" devices and matter is ipv6 based ? So i need IPV6 working in the LAN.

When my main ISP is connected (fiber), i set ipv6 to static with my box and it works well.
But when fail over switches to 5g box (dual wan), all ipv6 devices hangs on (Apple TV, iphone, ...) and do not access to the internet anymore.

I saw there is many IPv6 options in the router :

[IPv6] How to set up IPv6 in ASUS router? | Official Support | ASUS Global

How to setup this ?
I need it work well in the lan without blocking all apple devices when it swithces to fail over.
The main problem it that with static link to the fiber box, all apple devices can not go on the internet when il fails over to my 5g box.
And the 5g box has no ipv6 settings at all.

When y try static ipv6 witch works only with the fiber box, in the router ipv6 log a see all devices connected with ipv6 adresses.
But when i try non static ipv6 settings (native, passthrough, 6to4, 6rd), in the router ipv6 log there is zero devices connected via ipv6.

Perhaps in dual wan config, il would be needed to have specific ipv6 options for each internet box in the router.
So i could :
-do static ipv6 setting for main fiber box
-and disable ipv6 for second 5g box witch is an internet via cellular box with no possible ipv6 settings on the box side
So when dual wan switches to 5g box it would disconnect apple devices and make them reconnect with ipv4 adesses only.

Please help

 

[d5aqoep]

Dual WAN failover and fallback has historically never worked as intended. Best would be to avoid using it.

 

[doge]

OK, but i have no real choice, when my fiber is broken (few times a month),
i need to switch to second internet box (cellular).

So for now i use Native ipv6, with a lan IP set to my primary fiber box.
In this situation i just have to know that Matter devices (like Eve Energy) will simply not work when i am on the cellular wan.
In apple home app the Eve Energy become "unreachable" when fail over switches to the cellular box.

Fortunatly my fiber si repared in one or two days, so no big deal.

But, in my case, i note that changing my Eve Energy from HomeKit to Matter was not a good idea.
And i will avoid all matter devices (because they are all dependent on ipv6) for now, and stick with simple HomeKit with no Matter.

Best regards

 

[drabisan]

How do you get IPv6 from primary ISP? Prefix delegation? Or what other protocol?
Idea is: your router may not be the authoritative "voice" to redraw that subnet.
In theory when your router receive a PD from delegating router, it could (but not should) redraw that prefix from all clients.

In addition of dual WAN never being the most reliable feature, mixing a full stack (IPv4 and 6) with a IPv4 only stack is not a great idea.
I would guess if you're disable ipv6 on the primary link, failover works.

 

[doge]

For the main box (fiber) i use manual Prefix delegation, the second box (cellular) has no delegation settings.
Unfortunatly, in the GT-AXE16000 router there is no separate ipv6 sections now for WAN 1 and 2.
If there was, i would do delgation on first and disable ipv6 on second.

Thank you for advice

 

[drabisan]

Ah, now I understand even better. There's no way currently in AsusWRT to have such setup working. Fairly sure neither Merlin can do anything about it.
Your IPv6 is up and running no matter what. That subnet is not redraw when your primary WAN link goes down.

There are only 2 options: remove IPv6 or don't use at all the second WAN.

What you're looking to achieve is not easy at all even on high end Juniper or Cisco routers costing 100x more than a AXE16000.