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I have access to the IPv6 internet through Charter Communication's 6rd implementation. A number of CDNs fail to work correctly over IPv6, which causes a number of sites, including facebook, to have significant issues (pictures don't load, pages don't load, etc.)

On my desktop, I can disable IPv6, and these issues go away. Is it possible to do that on a stock android phone / tablet? (not rooted)

Edit: From the comments, I've learned that the actual issue is a MTU issue. So I'd be equally interested in a method to set a lower MTU on android as well.

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    I don't think you can disable IPv6 on Android, but you shouldn't have to. Facebook and other sites work fine over IPv6. It sounds like an MTU issue in your ISP's network, which they should fix.
    – Sander Steffann
    Mar 31, 2013 at 15:30
  • Unless you have a different method for detecting this (which I'd be glad to try), this site reports no PMTUD problems detected. I also don't think this is a MTU issue, because the connection always forms, but then no data is sent. I'll add an example of the problem to the post.
    – Bill Lynch
    Mar 31, 2013 at 15:41
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    Connections forming correctly but then no data being received is exactly what an MTU issue looks like. The connection setup (SYN, SYN+ACK, ACK) is with packets that are small enough to fit on any IPv6 link, but the data will be big enough to trigger the problem.
    – Sander Steffann
    Mar 31, 2013 at 20:52
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    @SanderSteffann: I just tested this, and a 1280 or 1400 MTU fixes the issue versus a 1500 MTU. So I guess I need to complain to my ISP then... If we have a method (which I assume we don't without rooting) to adjust the MTU on andriod, I'd be up for that as well.
    – Bill Lynch
    Mar 31, 2013 at 21:56
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    @SanderSteffann: As an additional side note, I was able to set a MTU of 1400 on my router, which looks like this will functionally solve my problem. Thanks so much! I guess I'll leave this open in case someone ends up having a method to do this on a per-device basis (which is actually a less preferred solution anyways).
    – Bill Lynch
    Mar 31, 2013 at 22:09

1 Answer 1

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Until Google does something about issue 1008, (which seems unlikely since it's about five years old now) you're unlikely to get a better answer, but for what it's worth, this might help someone in a similar situation.

At the moment you can't alter the MTU without root access to the device. In Linux this operation requires root, so on Android you either need to root the device, or Google needs to provide system functionality that applications can use to perform the operation (i.e. resolve issue 1008).

There is an off-market program MTUchanger which can be used on rooted devices to change the MTU. If you can root your device you can sideload this and work around the issue.

Of course, you should complain bitterly about Charter (and Rogers and the dozen or so other ISPs) deploying 6rd in 2013, when the rest of the world is moving past transition technologies and is doing native dual stack. 6rd is essentially ISP-private 6to4 tunnelling, which is why the MTU has to be lowered from 1500. As such, any company that deploys it is eventually going to have to do it again, and do it right.

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  • Seeing as how the situation hasn't changed in over a year, your answer appears to be the sad truth. Additionally, Charter is still deploying only 6rd in 2014.
    – Bill Lynch
    Sep 3, 2014 at 12:39
  • @sharth If they actually needed to deploy IPv6 via 6rd, it indicates that their network infrastructure is ancient, as the only legitimate reason to use 6rd at all is to pass traffic through routers that are so old they don't know what IPv6 is. And such routers are at least a decade old or more, largely thanks to a US government mandate that government agencies had to be IPv6-ready by 2008. Most enterprise network vendors had their hardware ready well before then.
    – Michael Hampton
    Sep 3, 2014 at 12:54
  • unfortunately, this answer talks about MTU, not about IPv6 which is the title of this question.
    – Frederick Nord
    May 4, 2015 at 10:25
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    @FrederickNord That's because this answer addressed the user's real question.
    – Michael Hampton
    May 4, 2015 at 17:38
  • As mentioned in the closed issue, Path MTU Discovery should be the proper thing to do (pending on kernel support I guess). Since nougat android should also respect the MTU value inside dhcp.
    – mirh
    Nov 6, 2019 at 13:44

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