Trying To Address/Fix Recent IPv6 Issues Causing Workstation Connectivity Problems RRS feed

  • Question

  • I am seeking assistance regarding a problem that I'm having difficulty discerning what the problem is:

    • random workstations on a client's network started experiencing problems with authenticating to the domain; PC's would get stuck sitting at the Welcome screen or would state that the PC/user could not be authenticated.    
    • Issue started about 1.5 months ago.  No changes have been made to the network or server; unless there was a Windows update that caused it.
    • I found the problem to be IPv6.  Disabling IPv6 on the workstation(s) immediately fixed the problem and does not re-occur as long as I leave it disabled.  Checking IPCONFIG /ALL on the workstations, I could see and verify that the NIC's had some random IPv6 address.  However, I'm not sure how it's getting it because their's no scope defined in DHCP.
    • This same issue was also causing some users to not be able to connect to their Exchange 365 server.
    • After checked the DHCP settings on the server (Windows Server 2008 R2), IPv6 is enabled with the green check, but there is no scope or any other settings listed underneath the tree.  Using IPCONFIG /ALL in my troubleshooting above, I could see that the IPv6 gateway was coming from the server's IP address.  This would lead me to believe that it is indeed the server's DHCP that is handing it out, and not some other device such as the firewall.
    • There are no settings within DHCP to disable the IPv6.
    • Checking the server's available NICs, none of them have IPv6 turned on and the primary connection had IPv6 disabled.

    At this point, I'm looking for some direction from someone with greater knowledge and experience on the matter.  Any help would be appreciated.  Thanks.

    Monday, February 2, 2015 3:02 PM


  • Hi Jason,

    >>I could see that the IPv6 gateway was coming from the server's IP address.

    Normally, if there is no IPv6 deployed, we should not get the IPv6 gateway.

    Have your ever configure the IPv6 address and IPv6 DNS on the server and client? If yes, please set them to obtain automatically. Windows 2008 R2 prefer IPv6 than IPv4, if we configure the IPv6 manually, it will use the IPv6 first.

    If the IPv6 setting is automatically obtained, please check which devices offers the IPv6 configuration.

    We can use Network Monitor to check this.

    Microsoft Network Monitor 3.4 (archive)

    Best Regards.

    Steven Lee 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 Support, contact

    Tuesday, February 3, 2015 7:39 AM