NCSI False "no internet" status

David Harron 26 Reputation points
2020-08-05T16:12:00.11+00:00

NCSI falsely says that a Windows 10 computer does not have internet even though it does and I can access both http://www.msftncsi.com/ncsi.txt and http://www.msftncsi.com/ncsi.txt test sites through a web browser.
This is a problem because Office 365 checks NCSI before trying to access the internet when it tries to activate.
How can I force NCSI to acknowledge that this PC is on the internet, or alternatively, force 365 to look on the internet to activate?

Windows 10 Network
Windows 10 Network
Windows 10: A Microsoft operating system that runs on personal computers and tablets.Network: A group of devices that communicate either wirelessly or via a physical connection.
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  1. Sunny Qi 10,896 Reputation points Microsoft Vendor
    2020-08-06T05:57:47.933+00:00

    Hi,

    Thanks for posting here.

    Network Connectivity Status Indicator (NCSI) is designed to be responsive to network conditions, so it examines the connectivity of a network in a variety of ways. One test failed, NCSI may report a error, even if the networking actually can be accessed fully.

    Sometimes, we can access the http://www.msftncsi.com/ncsi.txt file in IE, but the NCSI still fails. It is because the NCSI traffic is not sent via IE but via WinHTTP component and use proxy specially. A proxy server which requires user authentication won't allow it access Internet. Basically, NCSI must perform extra steps in an environment that has proxy servers. Web Proxy Automatic Discovery (WPAD) proxy detection is recommended. If WPAD is not used, configure WinHTTP proxy settings to help NCSI:

    netsh winhttp set proxy command

    For how to disable NCSI, please kindly refer to the workaround in the following article:
    https://support.microsoft.com/en-us/help/4494446/an-internet-explorer-or-edge-window-opens-when-your-computer-connects

    Meanwhile, I found another article related to Microsoft Connection Test (NCSI) and office 365 for your reference.
    https://purepcs.co.uk/kb/microsoft-connection-test-ncsi-and-office-365/
    Please Note: Since the websites are not hosted by Microsoft, the links may change without notice. Microsoft does not guarantee the accuracy of this information.

    Hope my answer will help you.

    ---Please Accept as answer if the reply is helpful---

    Best Regards,
    Sunny

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  1. David Harron 26 Reputation points
    2020-08-06T19:09:02.923+00:00

    Thank you SunnyQi for the great links describing the exact way NSCI works and the super detailed help.
    The last link that described disabling the IPv4 checksum offload resolved the issue for me.
    I really appreciate it, this issue was driving me insane.
    Regards,
    David

    1 person found this answer helpful.
  2. Ryan - CaspianITG.com 0 Reputation points
    2023-02-03T02:22:15.5366667+00:00

    Solution: I've had a similar issue with the internet working but no normal icon for networking. Found out that www.msftncsi.com was a point that needed to be communicated with but not via the HTTP protocol. Rather through ICMP. I noticed if I set my computer to automatically get an IP the icon went away because a firewall-assigned DNS server was assigned to my nic. As soon as I set it static and DNS back to 127.0.0.1 it came back after rebooting with the error. My system was behind a firewall and ICMP traffic outbound was blocked. Soon as I unblocked that traffic, opened a cmd prompt, and typed "ping www.msftncsi.com" the error icon instantly disappeared and everything worked. I verified before opening ICMP on the firewall that the Wireshark logs were showing "no response" from that "WWW' address. As soon as I lifted the restriction it worked after the ping.

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