I did what Asus tech support asked and reinstalled 7266 on my RT-AC88U and this is what happened

[Gregory Phillips]

I lost my IPv6 connection to Comcast just like I did in the beginning on the very first day I unboxed this router and it advertised the newer firmware. Right after it finished flashing I logged back into the UI and lo and behold I no longer had an IPv6 address assignment. I immediately reflashed the unit to Merlin's 380.65_2 and when I logged in I had IPv6 back just like before.

I'm not certain about what the stock firmware is doing in native mode but using Merlin's firmware it will immediately obtain an IPv6 connection that remains stable for days. I've only run the router a max of 6 days straight under any one firmware but Merlin's 380.65_2 has worked the best for me overall and that is what I'm running right now. I'm not at all inclined to switch back to anything that Asus releases. I don't know what part of prefix designation they don't understand over there but Merlin certainly does as his firmware has custom settings for it.

 

[TonyH]

There is no rule about firmware update. If you need for update according to the release note, you do it to get the benefit or if all is well with existing firmware there is no reason you must update. For me I only update firmware when there is need for that. Even at that, I wait until it is proven by other users.

 

[Gregory Phillips]

All very true but Asus asked me to run it and to send them the logs if I had issues which I did. I'm not the only person with Comcast who's complained about how they handle obtaining an IPv6 address and this issue seems to span several different router models.

 

[Deleted member 22229]

I lost my IPv6 connection to Comcast just like I did in the beginning on the very first day I unboxed this router and it advertised the newer firmware. Right after it finished flashing I logged back into the UI and lo and behold I no longer had an IPv6 address assignment. I immediately reflashed the unit to Merlin's 380.65_2 and when I logged in I had IPv6 back just like before.

I'm not certain about what the stock firmware is doing in native mode but using Merlin's firmware it will immediately obtain an IPv6 connection that remains stable for days. I've only run the router a max of 6 days straight under any one firmware but Merlin's 380.65_2 has worked the best for me overall and that is what I'm running right now. I'm not at all inclined to switch back to anything that Asus releases. I don't know what part of prefix designation they don't understand over there but Merlin certainly does as his firmware has custom settings for it.

Had the exact same issue with my 3100 when i had comcast. Something has changed either with comcast or the firmware itself for the last several builds. The stock Asus firmware version 858 works with v6 with no issues at all if you want to try that firmware its on the support sight for your model. In fact 858 works great all the way around all though there have been security patches since then that you may want to consider.

Im only using my 3100 as an AP now so i may even revert back to 858 as security is not as much of an issue when running in AP mode and my gateway handles fire walling and security.

 

[Gregory Phillips]

When I received my router it had 3341 installed which prevents rolling back to any older versions of the firmware. My only options are 3341, 3941, 4180 and 7266 all of which I've tried and none work right on Comcast.

 

[Deleted member 22229]

You can still rollback i have done it many times.

https://www.reddit.com/r/HomeNetwor..._to_downgrading_from_the_asuswrt_380_version/

 

[Gregory Phillips]

Hey thanks for that information.

 

[Deleted member 22229]

No prob. works like a charm.

 

[sfx2000]

I lost my IPv6 connection to Comcast just like I did in the beginning on the very first day I unboxed this router and it advertised the newer firmware. Right after it finished flashing I logged back into the UI and lo and behold I no longer had an IPv6 address assignment. I immediately reflashed the unit to Merlin's 380.65_2 and when I logged in I had IPv6 back just like before.

Comcast (and other providers that have closely followed Comcast's lead - yes, CoxHSI, I'm referred to you) have had interesting issues with IPv6 - it's getting better...

Quick Hint/Tip with Comcast/CoxHSI - make some changes on the Router/AP like OP mentioned - after rebooting the router, which happens because of the firmware change - take a moment to power cycle the cable modem - it does help here...

 

[Deleted member 22229]

Nope there is something in the newer builds that has changed at least with the 88U and the 3100. The older firmware mentioned works perfectly every time with v6. But have to agree this whole v6 deployment has been a joke so far and even today for most is not even needed and can be disabled. On a surprise im forced with uverse internet ATT and there V6 seems to work very well. Strange..

 

[sfx2000]

On a surprise im forced with uverse internet ATT and there V6 seems to work very well.

AT&T has done a nice job with their IPv6 on the wireless side, and I can't imagine they would be any different on the uVerse/DSL side, as they're essentially one network these days -- mobility and broadband.

My beef with Comcast/CoxHSI is more to do with their lack of testing against BSD oriented devices - there it has been a bit of a mess...

 

[Deleted member 22229]

Agree : - )

 

[KevTech]

My only options are 3341, 3941, 4180 and 7266 all of which I've tried and none work right on Comcast.

I have Comcast and have zero issues with IPv6 with any of those firmware you listed.

Sometimes after enabling IPv6 you need to reboot the router and/or the modem.

I am on 7378 right now and IPv6 works flawlessly just like it did with all prior firmware versions.

 

[Deleted member 22229]

I have Comcast and have zero issues with IPv6 with any of those firmware you listed.

Sometimes after enabling IPv6 you need to reboot the router and/or the modem.

I am on 7378 right now and IPv6 works flawlessly just like it did with all prior firmware versions.

Do you have the 88U or the 3100 ??

 

[MarkRH]

Do you have the 88U or the 3100 ??

According to the signature on the post, the RT-AC68U B1 unless the sig is out of date or something.

 

[sfx2000]

I have Comcast and have zero issues with IPv6 with any of those firmware you listed.

With Comcast - it's kind of a regional thing as they roll out stuff...

Not much different than other nationwide providers here in the US...

 

[Gregory Phillips]

I have Comcast and have zero issues with IPv6 with any of those firmware you listed.

Sometimes after enabling IPv6 you need to reboot the router and/or the modem.

I am on 7378 right now and IPv6 works flawlessly just like it did with all prior firmware versions.

I can tell you that where I am at on my RT-AC88U none of the factory firmware would establish an IPv6 connection except for 7266 but it would drop it after a few minutes. I had to hard reset the router to get it to even do that much. Moving to Merlin's firmware it does it straight away as his has lots of IPv6 specific settings that the stock firmware does not have.

 

[Gregory Phillips]

I'm back on 7266 right now and even though I cannot establish an IPv6 connection to Comcast I did notice that while running acrylic that my 2.4ghz network signal is stronger than on any Merlin version I've used. I think that the next step is to replace my cable modem with a newer model.

 

[Gregory Phillips]

I am going to replace my sb6121 cable modem today with a netgear cm1000 to eliminate it from the mix. I've been seeing too many strange issues surrounding my IPv6 connectivity the past couple of days plus its an EOL device with no support on Comcast. The netgear will be around for years to come with support so its time to make a change.