GetIsNetworkAvailable() behaves differently depending on NET version on Win11 LTSC.

Question

GetIsNetworkAvailable() behaves differently depending on NET version on Win11 LTSC.

Ming Liang 61

we have a project using the following function call.

On a Win11 LTSC test unit with no network connection:

Project built with NET 8.0, function GetIsNetworkAvailable() returns false

Project built with NET 9.0, function GetIsNetworkAvailable() returns true

  var isNetworkAvailable = NetworkInterface.GetIsNetworkAvailable();

Why GetIsNetworkAvailable() behaves differently? How to make GetIsNetworkAvailable() returns false when the project is built with NET 9.0? Thanks.

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Answer 1

Jack Dang (WICLOUD CORPORATION) 14,960 Microsoft External Staff Moderator

Hi @Ming Liang ,

Thanks for reaching out.

In .NET 8, NetworkInterface.GetIsNetworkAvailable() checks for active network adapters with an IP address. In .NET 9, the function was updated internally to also consider certain virtual adapters or system networks, which can make it return true even if the computer isn’t connected to the internet.

You can manually check for active, non-virtual network interfaces with a simple filter, for example:

using System.Net.NetworkInformation;

bool isNetworkReallyAvailable = NetworkInterface
    .GetAllNetworkInterfaces()
    .Any(ni =>
        ni.OperationalStatus == OperationalStatus.Up &&
        ni.NetworkInterfaceType != NetworkInterfaceType.Loopback &&
        ni.NetworkInterfaceType != NetworkInterfaceType.Tunnel
    );

Hope this helps! If my answer was helpful - kindly follow the instructions here so others with the same problem can benefit as well.

Ming Liang 61 Reputation points

2026-02-08T01:47:21.2066667+00:00
@Jack Dang (WICLOUD CORPORATION)
Thanks a lot.I tried you code example on my Win11 with NET.90.
It still returns true when there is no internet connection.

I guess for NetworkInterface.GetIsNetworkAvailable() to return false in NET9.0, following conditions should be met, Is that correct?

There is no virtual adapters or system networks.

Disable all the network adapters in Device Manager.
Jack Dang (WICLOUD CORPORATION) 14,960 Reputation points Microsoft External Staff Moderator

2026-02-09T06:25:37.2366667+00:00

Hi @Ming Liang ,

Thanks for the follow-up and for trying the code.

On some systems, .NET 9 can still return true even if there’s no internet. That’s because it counts all “up” network interfaces, including some hidden system adapters, not just real Wi-Fi or Ethernet connections.

Turning off all adapters would work, but it’s not practical. A more reliable way is to combine the filtered adapter check with a quick connectivity test, like trying to reach a small known website. That gives you a true sense of whether the network is really available.

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GetIsNetworkAvailable() behaves differently depending on NET version on Win11 LTSC.

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