C# Signature:

    [DllImport("mpr.dll", CharSet = CharSet.Unicode)]
    [return: MarshalAs(UnmanagedType.U4)]
    static extern int MultinetGetConnectionPerformance(
        NetResource lpNetResource,
        ref NetConnectInfoStruct lpNetConnectInfoStruct);

User-Defined Types:

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
    public struct NetConnectInfoStruct {
        public int cbStructure;
        public WNCON dwFlags;
        public int dwSpeed;
        public int dwDelay;
        public int dwOptDataSize;
    }

    [Flags]
    public enum WNCON {
        /// <summary>
        /// In the absence of information about the actual connection,
        /// the information returned applies to the performance of the
        /// network card.
        /// If this flag is not set, information is being returned for
        /// the current connection with the resource, with any routing
        /// degradation taken into consideration.
        /// </summary>
        FORNETCARD = 0x00000001,

        /// <summary>
        /// The connection is not being routed.
        /// If this flag is not set, the connection may be going through
        /// routers that limit performance. Consequently, if
        /// WNCON_FORNETCARD is set, actual performance may be much less
        /// than the information returned.
        /// </summary>
        NOTROUTED = 0x00000002,

        /// <summary>
        /// The connection is over a medium that is typically slow (for
        /// example, over a modem using a normal quality phone line).
        /// You should not set the WNCON_SLOWLINK bit if the dwSpeed
        /// member is set to a nonzero value.
        /// </summary>
        SLOWLINK = 0x00000004,

        /// <summary>
        /// Some of the information returned is calculated dynamically,
        /// so reissuing this request may return different (and more
        /// current) information.
        /// </summary>
        DYNAMIC = 0x00000008,
    }

    const int WNCON_FORNETCARD = 0x00000001;
    const int WNCON_NOTROUTED = 0x00000002;
    const int WNCON_SLOWLINK = 0x00000004;
    const int WNCON_DYNAMIC = 0x00000008;

Alternative Managed API:

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Notes:

Don't forget to initialize cbStructure member.

        NetConnectInfoStruct ci = new NetConnectInfoStruct();
        ci.cbStructure = Marshal.SizeOf(ci);

Tips & Tricks:

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Sample Code:

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