/// <summary>
/// Indicates whether any network connection is available
/// Filter connections below a specified speed, as well as virtual network cards.
/// </summary>
/// <returns>
///     <c>true</c> if a network connection is available; otherwise, <c>false</c>.
/// </returns>
public static bool IsNetworkAvailable()
{
   return IsNetworkAvailable(0);
}

/// <summary>
/// Indicates whether any network connection is available.
/// Filter connections below a specified speed, as well as virtual network cards.
/// </summary>
/// <param name="minimumSpeed">The minimum speed required. Passing 0 will not filter connection using speed.</param>
/// <returns>
///     <c>true</c> if a network connection is available; otherwise, <c>false</c>.
/// </returns>
public static bool IsNetworkAvailable(long minimumSpeed)
{
   if (!NetworkInterface.GetIsNetworkAvailable())
       return false;

   foreach (NetworkInterface ni in NetworkInterface.GetAllNetworkInterfaces())
   {
       // discard because of standard reasons
       if ((ni.OperationalStatus != OperationalStatus.Up) ||
           (ni.NetworkInterfaceType == NetworkInterfaceType.Loopback) ||
           (ni.NetworkInterfaceType == NetworkInterfaceType.Tunnel))
           continue;

       // this allow to filter modems, serial, etc.
       // I use 10000000 as a minimum speed for most cases
       if (ni.Speed < minimumSpeed)
           continue;

       // discard virtual cards (virtual box, virtual pc, etc.)
       if ((ni.Description.IndexOf("virtual", StringComparison.OrdinalIgnoreCase) >= 0) ||
           (ni.Name.IndexOf("virtual", StringComparison.OrdinalIgnoreCase) >= 0))
           continue;

       // discard "Microsoft Loopback Adapter", it will not show as NetworkInterfaceType.Loopback but as Ethernet Card.
       if (ni.Description.Equals("Microsoft Loopback Adapter", StringComparison.OrdinalIgnoreCase))
           continue;

       return true;
   }
   return false;
}