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IPv6 Setup with Comcast/Xfinity

Discussion in 'Asuswrt-Merlin' started by JohnD5000, Feb 22, 2020.

  1. Keenan

    Keenan Senior Member

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    Yes, I set it back to Native. I'm now trying to figure out why I'm not getting any IPv6 connectivity. I'm with Comcast as well.
     
  2. geobernd

    geobernd Occasional Visitor

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    I had this problem initially. Rebooting the Modem after the Router has already rebooted with IPV6 settings Native enabled fixed the issue and it has been working for me ever since (using a DPC3941B)
     
  3. Keenan

    Keenan Senior Member

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    Just tried that and it made no difference, still no connectivity. I suspect the issue is with the Comcast gateway device but I'm not sure what exactly what to look for.

    The below image is what my IPv6 page looks like.
     

    Attached Files:

  4. appleseed

    appleseed Regular Contributor

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    what's your gateway device, and is it in bridge mode ?
     
  5. JohnD5000

    JohnD5000 Regular Contributor

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    Where do you go to see this?
     
  6. Keenan

    Keenan Senior Member

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    It's a Technicolor CGM4140COM. The belwo link is to the FCC data sheet for it. It's a Comcast rental gateway which I've been using as it allows me to get unlimited data for $40 instead of the $50 per month when using my own modem. That $10 is looking more and more like a very weak reason to use their equipment. :rolleyes:

    https://fccid.io/G95CGM414X/User-Manual/User-Manual-3423718

    And yes, it's in bridge mode.
     
  7. appleseed

    appleseed Regular Contributor

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  8. appleseed

    appleseed Regular Contributor

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    You should be able to log in and see if you are pulling an ipv6 address:
    • Click on the Connection tab at the left of the screen
    Look for WAN IP Address (IPv6). If you don't see one then a restart should fix it.
    Comcast is probably now above 95% complete with residential ipv6.
     
  9. Keenan

    Keenan Senior Member

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    It does show an address there but I've restarted the modem a few times and those IPv6 test pages indicate no connection.
     
  10. appleseed

    appleseed Regular Contributor

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    on the router, try changing ipv6 Connection type to Disable then to Native
    may or may not need a restart in between
     
  11. appleseed

    appleseed Regular Contributor

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    are you running anything out of the ordinary on the router, (scripting like AMTM, VPN, FreshJr, PieHole, DNSCrypt, etc), or just basic home networking?
     
  12. Keenan

    Keenan Senior Member

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    Still nothing. The Comcast modem sees the address but for some reason, the router doesn't.
     
  13. appleseed

    appleseed Regular Contributor

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    If you're not running other things like scripts, I think your 86U needs a downgrade (or upgrade depending on what you're on). IPV6 should be working natively on the 86U, both Merlin and Asus default firmware.

    Only other thing to consider is free space on both your RAM and Flash. Sometimes when you connect a device like a drive, or add a number of devices to a static list, the router can behave wonky (technical term) as you approach RAM/Flash limits. Other times it's just a bad install that a reinstall should fix.
     
  14. EmeraldDeer

    EmeraldDeer Very Senior Member

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    The Cloudflare data center is in Boston.

    Should you switch from Quad9? Cloudflare does not do security filtering while Quad9 does. I am relying upon Diversion to do DNS filtering. Several months ago I was testing DNS over TLS with Quad9, CleanBrowsing and Cloudflare. Quad9 and CleanBrowsing were not reliable. At the time I was a paying customer of CleanBrowsing and had opened tickets, but to no avail.

    By the way, I am also using Cloudflare for NTP via "pool time.cloudflare.com"
     
  15. EmeraldDeer

    EmeraldDeer Very Senior Member

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    Try running the commands below. The issue which required these commands had been addressed, but I am not sure at which version.
    Code:
    echo "1" > /proc/sys/net/ipv6/conf/all/accept_ra
    echo "1" > /proc/sys/net/ipv6/conf/all/forwarding
    echo "1" > /proc/sys/net/ipv6/conf/eth0/accept_ra
    echo "0" > /proc/sys/net/ipv6/conf/eth0/forwarding
    
    If this were to work it would be immediate. You would see the values populate on the IPv6 tab in System Log.
     
    Last edited: Feb 22, 2020
  16. Keenan

    Keenan Senior Member

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    I downgraded to 384.14 and it made no difference.
     
  17. EmeraldDeer

    EmeraldDeer Very Senior Member

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    Yes, Router Advertisement assists IPv6 addressing on the LAN, not on the WAN. It is for SLAAC, which works differently from DHCP which is used for assigning addresses in IPv4.

    The DNS server settings you are referring to are just that, they are not settings related to the router's caching DNS server/forwarder.
     
  18. appleseed

    appleseed Regular Contributor

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    what happens when you try EmeraldDeer's suggestion - no change ?
     
  19. EmeraldDeer

    EmeraldDeer Very Senior Member

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    I am not sure this will be applicable to your location but for Comcast here:
    LAN IPv6 addresses begin with 2601
    WAN IPv6 address begins with 2001
    WAN IPv6 gateway address begins with fe80

    If your WAN IPv6 address begins with 2601, then perhaps bridge mode is not working.
     
  20. Keenan

    Keenan Senior Member

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    All those match what I'm seeing in the modem connection menu.