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DavidHarron-7344 avatar image
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DavidHarron-7344 asked AymericNicholas-9098 commented

NCSI False "no internet" status

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
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SunnyQi-MSFT avatar image
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SunnyQi-MSFT answered

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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DavidHarron-7344 avatar image
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DavidHarron-7344 answered AymericNicholas-9098 commented

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

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We've got the same issue here, the trick that described how to disabling the IPv4 checksum offload resolved the issue also. There is also a way to script it and then deploy it and make ti permanent, follow this link : https://social.technet.microsoft.com/Forums/lync/en-US/04cece81-3bd6-4f0d-9356-d26c2ffaa7ec/disable-ipv4-checksum-offload-from-command-or-script-on-windows-7?forum=w7itpronetworking

Thanks for you explanation and help.

1 Vote 1 ·

Hi,

Glad to hear that the information provided was worked for you.

If there is anything else we can do for you, please feel free to post.
 
Best Regards,
Sunny

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