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Cannot Access *.mail.yahoo.com with IPv6 enabled RRS feed

  • Question

  • I'm really baffled by this problem. I don't think it's a "windows 10 networking" problem, but I'm hoping some of the networking experts here might have some suggestions to help narrow down the cause of the problem.

    For the past few weeks, I've been unable to find the cause of not being able to access *.mail.yahoo.com with IPv6 enabled. This includes web access using any browser (IE, edge or chrome on a pc or chrome on a mobile phone), as well as using the yahoo mobile app or the gmail app on an mobile phone. Specifically, if I try to access mail.yahoo.com, the browser times out. If I disable IPv6 on the router or on a pc, I can access mail.yahoo.com with no problem.

    Up to a few weeks ago, this problem was not occurring. I didn't make any changes to any of the network that I have control over. My router is pfsense 2.3.2_1 (running on a hyper-v server), which uses a hurricane electric tunnel for IPv6. This morning, I completely disabled IPv6, dhcpv6 and the tunnel and reconfigured everything from scratch using a new tunnel from a different server. There was no change.

    I can ping and tracert -4 -6 mail.yahoo.com. It's reachable. I checked the routing and the mtu settings. I even tried reducing the mtu to the minimum (1280) but that made no difference. The mtu is back to the default of 1480 and ping -6 -l 1432 works.

    Since routing and mtu appear to be okay, something else must be wrong. Unfortunately, I can't figure out what. Is there anything that could be "swallowing" the response from the website? Is there any way to find out where it's being swallowed?

    Also, if I start up a dual-stack vpn (mullvad), I can access mail.yahoo.com. I also have a completely isolated test network running on the same hyper-v server, connected to the same gateway with its own ipv4 address and an ipv6 /56 prefix and I can access mail.yahoo.com. (For reasons I won't waste time on here, it's not possible to use this network.)

    I have posted on the pfsense and tunnelbroker forums but haven't found a solution.

    Anyone?

    Saturday, October 22, 2016 2:04 AM

Answers

  • Hi, 

    First, if you have any firewall enable, please test the results with firewall off. 

    What's the results of these commands? Please post back the results:

    nslookup https://mail.yahoo.com

    Then command:

    tracert mail.yahoo.com


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, November 3, 2016 2:18 PM

All replies

  • When you say 'connected to the same gateway with its own ipv4 address and an ipv6 /56 prefix and I can access mail.yahoo.com.' is that connected via the pfSense box as well? So then would client IP range be the only difference?

    Have you tried packet tracing a failed connection, what is the last thing in the failed connection? Thinking something the packet flow maybe upsetting yahoo and they drop the connection.

    Sunday, October 23, 2016 6:29 PM
  • Both pfsense routers are running on the same hyper-v server, sharing the same physical ethernet nic that's connected internally with a virtual switch and externally to a bridged port on the physical gateway. Aside from sharing the same wan port, they are completely independent. They both have separate ipv4 addresses. One is using an HE tunnel for ipv6 and the other is using native ipv6 with a /56 prefix (reduced to /64 by pfsense). The latter network is completely virtual including a virtual windows 10 client. I can access mail.yahoo.com from the native network, but not from the tunneled network. I'm completely stumped trying to figure out why, considering it had been working for several years until a few weeks ago.

    By packet tracing, are you referring to wireshark? If so, I haven't tried that yet.

    Sunday, October 23, 2016 8:50 PM
  • Hi,

    I noticed this article which states the issue that:

    http://www.networkworld.com/article/2221820/cisco-subnet/cisco-subnet-should-you-allow-inbound-e-mail-over-ipv6.html

    "If you do not have an IPv6-capable DNSBLs or an IPv6-capable SPAM filter then you may not want to allow inbound Simple Mail Transfer Protocol (SMTP) over IPv6. You may not want to operate an IPv6-enabled network in a less secure manner than you do today with IPv4. We should strive to establish the same security protections for IPv6 as we use today for IPv4. Furthermore, we should be keenly aware of where we lack IPv6 feature parity and avoid enabling IPv6 when it creates a security exposure."

    This could be your issue, please check the Firewall Settings or contact Yahoo support to know details about this issue.

    In addition, we can also check the network traces both Enabling IPv6 and not-Enabling IPv6, do the compare.

    Please use Network monitor to capture the trace when reproduce this issue:

    https://www.microsoft.com/en-sg/download/details.aspx?id=4865


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Monday, October 31, 2016 8:54 AM
  • Thank you for your reply. In this case, I'm not using SMTP. It's purely web access. Also, I can't even access the website (mail.yahoo.com). With chrome, it times out. With IE11 or edge, it hangs indefinitely.

    Monday, October 31, 2016 4:10 PM
  • I left ie11 and edge to see what would happen. They both timed out.

    Monday, October 31, 2016 6:58 PM
  • Hi, 

    First, if you have any firewall enable, please test the results with firewall off. 

    What's the results of these commands? Please post back the results:

    nslookup https://mail.yahoo.com

    Then command:

    tracert mail.yahoo.com


    Please remember to mark the replies as answers if they help and unmark them if they provide no help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, November 3, 2016 2:18 PM
  • Would you please share the further information required in my last post?

    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Sunday, November 6, 2016 11:06 PM
  • I have been seeing this same issue off and on for several months. This does not appear to be a Windows issue as I see the same thing on Windows, Mac, and Linux on any IPv6 enabled network. It will work from time to time, but most of the time fails.

    I have been trying to get in touch with their support people to open a ticket, but if you have ever tried to contact Yahoo support you know that this is virtually impossible to do...

    Friday, January 20, 2017 1:51 AM
  • I'm resurrecting this thread to report that I started having this issue with Yahoo a few days ago. Pages simply won't load.

    Disabling IPv6 or enabling TCP MSS clamping makes it work. However, neither are acceptable solutions in 2020. I managed to actually contact Yahoo support, but I have no idea if the issue was even understood.

    Thursday, August 6, 2020 9:19 PM