Make OpenWRT prefer to use IPV6 instead of IPV4

I've been messing around with my new Dynalink WRX-36 (very awesome device with the Agustin NSS build from github) and I was running some tests, including I have noticed on ALL my devices (phone, laptop, wired and wireless Desktops), that ipv4 is being preferred before falling back to ipv6.

On all my previous setups with different OpenWRT routers (Belkin RT1800, Archer c7 v5) in the same house and ISP ipv6 was preferred, and is my preference as well. Ipv6 sites are accessible and seem to load faster than ipv4 but still I am stuck with ipv4 as the preference.

For reference, I am using the SmartDNS package and Adblock-fast with great results but even when they are disabled from starting and the router is rebooted the results remain the same.

What is going on and why is this happening? I have the ability to post config files and am willing to experiment to have ipv6 as the preferred protocol.

Thank you very much for any help.

Ask whomever "Agustin NSS from github" is?

AgustinLorenzo, making great strides with qualcommax and OpenWRT, but that is not the problem. Using the SnapShot from the firmware selector and flashing that brings the same results.

Any suggestions?

There is no setting to prefer one or another stack, just that end clients may prefer one way or another and switch away from unreachable stack in varied timeframe.
You can back up config, upgrade to real OpenWRT resetting and recreating config.

And on it goes


Now this is interesting. Thank you.

I highly suggest you use the search here on OpenWrt and lookup AgustinLorenzo or look at the top thread on this subtopic with qualcommax in the title.

As I mentioned before I already tried the latest snapshot, even though Agustin is only a few days behind, and the same behavior was exhibited. I will continue my search for answers.

Thank you for your attempt at helping, even though you come off as very snobby.

Either you install a known version or go barf at another tree.

As others said, this does not have much to do with the router. Generally if an endpoint has been provisioned with a GUA and a v6 address of a DNS server (typically the router's link-local), it will prefer IPv6. So check the network status on your endpoints.


I will do that. Thank you. After refreshing the page,, multiple times in a row it switches from ipv6 preferred to ipv4 every now and then. My config is correctly set to use ipv6 and will if I force it (i.e.

Ipv6 DNS addresses, and popular websites with ipv6 IP, ping latency from the Dynalink are all consistently lower than ipv4, however. The response is faster and the services that provide ipv6 do seem snappier using them with ipv4 disabled completely on the devices. It's just strange that my browsers on all clients still prefer ipv4 sometimes when my tests results have shown that ipv6 will consistently respond faster coming straight from the OpenWRT device. It must be either all of my clients, my ISP or perhaps my config with this new device. More research is required.

I upgraded my cable modem very recently to an Arris SB8200 and noticed Xfinity gave me new IP's. My WAN IPs historically for years have been static so it may be because of the new modem; going from DOCSIS 3.0 to 3.1 may have triggered that, I am not an expert by any means so I do not know, hence why I am here asking for help.

I was considering it to be an OpenWRT issue, given the rapid development of the somewhat newly supported Qualcomm chipset in my device, and given that my last device running a snapshot from < a week ago (Belkin RT1800) served ipv6 consistently as preferred with the same setup, including the new cable modem, before I upgraded to the Dynalink.

I will tinker over the next few days when I have time and see what can be done. I'll post back with results and a solution if found.

Thanks for your productive input. I greatly appreciate it.

Firefox has 5s happy eyeballs timeout, chome 2s.

Yeah, I was messing around with the settings in different browsers and looked into how they handle dual stack connections and websites that offer both ipv4 and ipv6. I managed to get 'ipv6 default' listed on that site every time by changing the DNS Firefox uses to NextDNS over https through the baked in settings, even though that is one of the top DNS servers in my SmartDNS list, but I reflashed the snapshot from today for my device with DNSmasq-full as the only change (OpenWrt SNAPSHOT r26725-0a07a3a13d / LuCI Master 24.158.03388~a6f8361) and still without SmartDNS or AdBlock-Fast enabled, also my default config of Cloudflare servers used for both WAN and WAN6 DNS servers, I have the issue with this site telling me intermittently that I'm using ipv4 by default. I set the firewall rule to 'hi-jack DNS' via the OpenWRT article, even though SmartDNS already does that by default I wanted to be sure that with it off I was still using my ipv6 DNS servers.

I also signed into Cloudflare and Steam today through my phone connected to WiFi, Firefox with my own DNS servers used, no SmartDNS, and my 2FA warned me that my ipv6 address was attempting to login. So I'm not really trusting the results from that website. tells me everything is good and they have a link to a slew of ipv6 only sites with every single one I tried working no problems for me.

I contacted Xfinity and they escalated the issue after I explained in-depth what is causing me to be concerned about my ipv6 connection, blaming my cable modem at first but low-level Customer Service agents can't do much about my specific issue so I was expecting that.

I really feel that since my WAN Ipv6 address has changed there are no AAAA records of it on any of the major DNS servers, at least that's what my associate mentioned could be the culprit, and that website perhaps relies on those for it's results. I don't know.

I'm going back to the Agustin NSS build when the next update drops perhaps because it was giving me better latency in speedtests (minus ~10ms and killer jitter of <1ms with slightly better bufferbloat versus the snapshots) via wired and wireless, with excellent iperf3 results over 5Ghz to my HTPC (my most important rig in my WDS network wired to the Belkin RT1800 acting as a client). NSS works amazingly well with my device and Agustins specific builds/mods. I don't seem to be missing out on much with his compiled snapshots/mods since the snapshot runs on kernel mods mostly and there's much more than I thought that just can't be installed through opkg conveniently when an OpenWRT device is operating that way, at least with the WRX-36 and qualcommax builds.

My ISP plan doesn't really take full advantage of NSS however, (150mbps down 20mbps up, ~170mbps down and ~30mbps up in reality) but I plan on upgrading my speeds after finding a good value with Xfinity (lol) or perhaps another ISP as soon as possible. Maybe not, because I'm honestly fine with the speeds I have and no data cap at all, since I frequently use 2TB or more a month. 1.2TB cap with $10/50GB over can suck a fat one.

My associate with a Master's in Computer Science or whatever told me to just keep using the internet as I am since I'm able to reach out and interact with ipv6 only sites and services so I really don't have any problems. He told me that if anything Xfinity may send out someone to check out the neighborhood network cabinet and tune it up for optimal performance, if it's been a while since maintenance or something. Or they'll get me a AAAA DNS record I guess. He's so talented it's hard for me to decipher what he's saying even when he attempts to dumb down things, for the moment at least. I have a high motivation to learn as much as I can about everything and always have, networking is my new thing now.

I actually logged into Hurricane Electric today, ipv6 connection of course, and set up a reverse proxy DDNS that points to my HTPC with it's static ipv6 address and it works fine. I think that website is just not trustworthy with it's results as the Google ipv6 test site as well says "Great, you're already using ipv6" or something along those lines, along with the other ipv6 test site telling me I have no problems with ipv6.

Maybe I simply need to ignore that one website telling me about the ipv6 fallback. We'll see what Xfinity does, they're going to reach out to me soon I was told.

Thanks for the new terminology by the by, 'happy eyeballs'. I'm learning so much from this forum and it's community while I work on my own degree.

Maybe there's no problem at all and I'm overreacting to one website's test results; that's just full of crappy banner ads without my adblock-fast turned on. The internet SUCKS without a local network wide adblocker or uBlockOrigin running, I've noticed. I don't know how people do it, it's a nightmare.

I know, I know, rambling post but I can't sleep. I think I'm going to fire up Lies of P and forget about it for now. I will post back with what happens though. I'm thinking I'm just overreacting to the results and it's all good.

If there are any other tests or things I should try to see if there is a real problem with my ipv6 let me know, I obviously want ipv6 by default. It's the future of the Internet and from my understanding much better than defaulting to ipv4 only any day.

Nothing to do with address families, your CPU is good enough to approach gigabit with default (no-nss) OpenWRT and soft offload. Even better (i dont know, you have to try) if irqbalance and/or packet steering spreads load aming CPU cores evenly.

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I don't like, is much more streamlined and answers the basic question of whether the v6 Internet is reachable.

Also my experience with Xfinity (Business) is that the customer's IPv4 is reserved but they issue different IPv6 every time the modem loses connection. An interesting trick is you can get multiple (but random) /60s on the same line by making additional DHCPv6 requests with a different clientid.

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I'm starting to become a believer of that myself.

I'm trying that today when I get home. Just change to /60 huh?

I believe I get static ipv6 as I'm on Xfinity home plan, but when I get off work I'll check out my 2FA logs and see what IPs have logged into it via ipv6, or maybe I have a screenshot of my interfaces page from pre Arris sb8200.

I noticed in the qualcommax thread that the NAPI in the NSS builds is actually hurting iperf 5Ghz Wireless performance slightly when measured in April by a random user, I believe. Maybe NSS isn't what it's cracked up to be just yet.

Speed was over a gigabit with hard and soft offloading and packet steering enabled on all CPUs with 5Ghz at 1W (30dbm) power (I was gifted the power of Zeus from another user via an ipk mod for transmission power) on the NSS build. I'll try it again when I get home.

So far nothing is different at all with the snapshot vs NSS. I have packet steering on with the suggested 128 RPS, hard and soft offloading as well, recommended by another user for this device regardless of build and it's great. I thought those were settings any decent device should have turned on? The soft and hard offloading worked wonders on my Archer c7 v5 but it got a little warmer to the touch under long wireless LAN transfers, no burning smell or anything just warmer to the touch. Packet steering gave me strange latency spikes to 600ms sometimes under load with that one. You're right, I'll have to test it from now on.

I see the WRX-36 is only $80 on Amazon brand new now but I have my eyes on a Netgear RAX120v2 for <$40. That's the prize right there for qualcommax. That router is tits with the hardware it has.

Try non-nss, it should approach gigabit, albeit with significant CPU consumption.

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The new @AgustinLorenzo NSS Build Dropped and I couldn't help myself. Of course I backed up my old config and all that first but after flashing it and getting all my things setup, the site gives me ipv6 as the default now every time. I believe the development of qualcommax is simply maturing more and more and I'm just enjoying the ride. Maybe the OOTB setup with the newer snapshots is just better than what I had to do previously to even get ipv6 functional. Or maybe Xfinity did something on their end to 'fix' my ipv6.

The build is fantastic and NSS really does a make a difference. When I'm streaming games like Lies of P from my Main rig to my laptop two stories down with moonlight on 5Ghz Wifi, channel 36 160Mhz, it's flawless, even at a steady 167fps at 1440p, there's zero noticeable latency. Iperf3 is as expected at ~1 gigabit under ideal circumstances and I couldn't be happier.

I'd still like some kind of correspondence with Xfinity to see if they actually did anything or if they plan to.

I read the document/draft about RFC6724 and that was interesting for sure. 8 drafts over the years, much dedication.

Thanks for all the guidance and information. Appreciate you all.