Detect When Network Goes Up or Down

namespace My
{
 internal partial class MyApplication
 {
  private void MyApplication_NetworkAvailabilityChanged(object sender, Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs e)
  {
   if (e.IsNetworkAvailable) {
    Diagnostics.Debug.WriteLine("Network went up.");
   } else {
    Diagnostics.Debug.WriteLine("Network went down.");
   }
  }
  public MyApplication()
  {
   NetworkAvailabilityChanged += MyApplication_NetworkAvailabilityChanged;
  }
 }
}