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Dual WAN with only one internet connection!?

Level 9

(edited: changed Verizon FiOS to AT&T Fiber)

I have two GT-AX11000 routers, one set up as the main router and the other as a wired Access Point.  Ever since switching from Spectrum to Verizion FiOS AT&T Fiber for internet services, my main router will periodically lose internet connection (every 5 days or so) rendering every network device that relies on internet (wired or wireless) unusable.  The only solution seems to be to reboot the main router.  Then everything goes back to normal.

As a partial solution, I enabled the Reboot Scheduler on both routers so that they reboot every night at 4am.  This helps but does not completely eliminate the problem.  My internet now drops out every 15 days or so.

My theory is that the FiOS AT&T modem is to blame, but I'm not 100% sure.  It's a modem/router combo, and to get it to work with my GT-AX11000, I have to set the FiOS AT&T modem to "passthrough" (the Spectrum modem/router had more features and I could set it to "bridge" mode which worked flawlessly).  But every so often, it disconnects my GT-AX11000 and everything downstream.  My internet works just fine up to the FiOS AT&T device, but somehow my GT-AX11000 loses its connection.

Anyway, last night I tried a new solution that I'm hoping will work.  I enabled Dual WAN on my main GT-AX11000 router and ran a SECOND ethernet cable from my FiOS AT&T router to one of the LAN ports of my main GT-AX11000 router.  In other words, my main GT-AX11000 router is connected to the FiOS AT&T modem TWICE: once via the WAN port and once via LAN 1.

I set the Dual WAN mode to "Fail Over" and enabled "failback".  I then set my Auto Network Detection settings to 5 seconds, 12 attempts (4 attempts for failback), and set Network Monitoring to DNS Query.

I did a quick test to see if the setup would work by unplugging the Primary WAN ethernet cable from the back of the FiOS AT&T modem, and sure enough after 60 seconds, my router switched over to the Secondary WAN connection (which is also connected to the FiOS AT&T modem).  Everything was working great.

I then plugged the Primary WAN ethernet cable back into the FiOS AT&T modem, and soon afterwards, my router switched back over to the Primary WAN connection.

Amazing, right?  Well.... maybe.  I still have to see if this will work under real world conditions, but I'm hopeful this workaround will keep my disconnections to a minimum.  If this works as I hope it does, in theory I would only be disconnected for a maximum of 60 seconds and everything would reconnect automatically.  My routers will still automatically reboot each night at 4am, just to reset all connections.

It's very possible though that when my Primary WAN loses its connection under real world conditions, the Secondary WAN connection will also drop.  Anyway.... fingers crossed.

Has anyone else tried connecting their router to the same modem twice and enabled WAN??


Level 11

We have Frontier at another home.  It came with Eeros included with the pricing so I never attempted to connect any ASUS router product to it.  The “modem/router” must be connected in order for the service to work?  Or can/have you try/tried connecting the ASUS router directly to the ONT?

Sorry, I don't know why I said Verizon FiOS.  My brain is not working.... I set up my parents with Verizon FiOS.  I have AT&T Fiber (and switched from Spectrum).

In any case, to answer your question, I think the AT&T device I was given is an ONT/modem/router in one.  I cannot bypass it as far as I'm aware.  The fiber optic cable terminates into an SFP port on the back of the device and I plug my GT-AX11000 into it.

this is what it looks like (photo grabbed from the internet, but identical to mine).



That's one fancy ONT/router!

I Googled "BGW320-505" and found this interesting page:

Section 2.2 shows proper settings for IP Passthrough and a setting called "DHCPS-fixed" .  I have no idea what that is, just only starting to look it up.  But I don't want to assume you've not set it up this way, nor want to assume that you did...

yeah, mine's set up that way.  i spent tons of time reading about how to configure it and followed the advice on various forum threads, etc.  it still disconnects periodically.  for whatever reason, the two devices have trouble communicating after a while, and i've mostly given up trying to understand why.  there is apparently a way to bypass the AT&T device, but it's very involved and beyond my technical capabilities.

the Reboot Scheduler makes the problem tolerable, and hopefully this dual WAN workaround will eliminate it entirely (i have my doubts though).

I was wondering if you had asked AT$T for a modem rather than a Gateway?

You have not been able to find a User Interface for the Gateway?

If the Gateway is disconnecting at specific times, there should be something in your Router log.  Possibly they are renewing the IP addresses?

Why would the Gateway disconnecting disturb your internal network?   Do you use any Wi-Fi from the Gateway?

I currently have Spectrum with AT$T at the back door, so I will be watching your experience.  I have seen threads which seem to be related to your same problem, so hopefully the problems get worked out.


Maximus Z790 Hero,
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Intel AX411

@Saltgrass wrote:

I was wondering if you had asked AT$T for a modem rather than a Gateway?

The AT&T installer told me that this was the unit they provided.  I'm not sure if I can switch it out with a basic modem.... I guess I can ask, but I doubt it.  The gateway converts the optical signal of AT&T's fiber network into a signal my router can use.


@Saltgrass wrote:

You have not been able to find a User Interface for the Gateway?

I can log into the gateway and configure it, yes.  And I have.  I've tried all sorts of configurations and read dozens of forum posts about how best to set everything up.  It still disconnects from time to time.


@Saltgrass wrote:

If the Gateway is disconnecting at specific times, there should be something in your Router log.  Possibly they are renewing the IP addresses?

Why would the Gateway disconnecting disturb your internal network?   Do you use any Wi-Fi from the Gateway?

I haven't been checking my router logs.  The next time it happens, I'll have to remember to take a look.

The gateway disconnecting does not disrupt the internal network.  Did I say it did?  It disrupts internet access for all devices on the network.

And no, I don't use wi-fi from the gateway.  Wifi on the gateway is off.  The gateway is set to passthrough mode.

Level 11

I wanted to address your question:  my modem only has one 2.5 Gbps port here (Giggle Fiber) at my parents’ house.  Frontier provided us with a Nokia ONT with one 10 G port which connects to an Eero 6 Pro.  There are 4 what look like LAN ports (grouped together) but I never touched them…

As I know there are two settings for connecting two WANs:  dual WAN and WAN aggregation.  I had dual WAN enabled when a tree branch knocked our cable line down.  It did not automatically switch over until I physically disconnected the Ethernet cable connection from the modem to my router.  BUT (by default) the DNS query and Ping checkboxes were unchecked.  (Yesterday I selected DNS query like you).

I wonder how WAN aggregation reacts to your issue, (I guess if AT&T allows simultaneous connection).

I'm pretty sure Dual Wan will only work properly if Auto Network Detection is enabled.  If you had it set to off, that might explain why your internet didn't switch over.

I'm not sure if Wan Aggregation is relevant here because I'm not trying to increase my internet speeds.  I'm simply looking for a way for the router to reestablish its connection with the gateway when it drops out.  The Auto Network Detection feature of Dual Wan is the mechanism I'm interested in.  In theory, it should trigger a switch to my secondary gateway connection when the primary connection fails.  And back to my primary connection when the connection is restored.  Now... will it actually do that?  That is the question!  Hopefully yes.... still too soon to tell.  I only enabled dual wan yesterday.  We'll see how long before my primary connection disconnects.  I suspect it will take at least another week.