GetIsNetworkAvailable() behaves differently depending on .NET version

[liangming2003]

Description

We have a project using following function call:

var isNetworkAvailable = NetworkInterface.GetIsNetworkAvailable();

On a Win11 LTSC (W11 IoT Enterprise LTSC) test unit with no network connection (Ethernet cable unplugged and Wi-Fi not connected).

When the project is built with .NET 8.0, the function GetIsNetworkAvailable() returns false.
When the project is built with .NET 9.0, the function GetIsNetworkAvailable() returns true.

Here is Microsoft support's explanation on why GetIsNetworkAvailable() behaves differently depending on .NET version:
https://learn.microsoft.com/en-gb/answers/questions/5763874/getisnetworkavailable()-behaves-differently-depend

We like to keep the function behavior of .NET 8.0 when building the project with .NET 9.0. Is there any equivalent code to replace the function GetIsNetworkAvailable()? Or, This is a bug that will be fixed in a later version. Thanks.

Reproduction Steps

var isNetworkAvailable = NetworkInterface.GetIsNetworkAvailable();

On a Win11 LTSC (W11 IoT Enterprise LTSC) test unit with no network connection (Ethernet cable unplugged and Wi-Fi not connected).

When the project is built with .NET 8.0, the function GetIsNetworkAvailable() returns false.
When the project is built with .NET 9.0, the function GetIsNetworkAvailable() returns true.

Expected behavior

On a Win11 LTSC (W11 IoT Enterprise LTSC) test unit with no network connection (Ethernet cable unplugged and Wi-Fi not connected).

When the project is built with .NET 9.0, the function GetIsNetworkAvailable() returns false.

Actual behavior

On a Win11 LTSC (W11 IoT Enterprise LTSC) test unit with no network connection (Ethernet cable unplugged and Wi-Fi not connected).

When the project is built with .NET 9.0, the function GetIsNetworkAvailable() returns true.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[dotnet-policy-service]

Tagging subscribers to this area: @karelz, @dotnet/ncl
See info in area-owners.md if you want to be subscribed.

[wfurt]

This seems to be side effect of including more interfaces. I think we should also filter out all interfaces that do not have IP address. That still may leave some VPN in the list. Alternatively, for this purpose we may use the original interface list - the motivation for including more interfaces was ability to list disabled interfaces - and that should be irrelevant for this purpose.

[liangming2003]

@wfurt

Here is the code we currently use to replace GetIsNetworkAvailable() in .NET 9.0 project. It seems to work , but does the code has the same function behavior of .NET 8.0's GetIsNetworkAvailable() ?

          //var isNetworkAvailable = NetworkInterface.GetIsNetworkAvailable();

           var isNetworkAvailable = NetworkInterface.GetAllNetworkInterfaces()
                                                    .Any(ni =>
                                                         ni.OperationalStatus == OperationalStatus.Up &&
                                                         ni.NetworkInterfaceType != NetworkInterfaceType.Loopback &&
                                                         ni.NetworkInterfaceType != NetworkInterfaceType.Tunnel &&
                                                         ni.Supports(NetworkInterfaceComponent.IPv4) &&
                                                         ni.GetPhysicalAddress().ToString() != null &&
                                                         ni.GetIPProperties().GatewayAddresses.Count > 0 &&
                                                         ni.GetIPProperties().UnicastAddresses.Count > 0 );

[wfurt]

This is best approximation I could come up with in 5 minutes reading the issue and looking around. I think this will need some more thinking @liangming2003 before we can make any specific claims. I'll put it into 11 bucket so it stays on our radar.