detect Internet Connection/Disconnection in Console App C#

detect Internet Connection/Disconnection in Console App C#

I wrote a small console app which connects with a remote site, downloads
some data and process it. As it is network operation so I want my
application to be intelligent enough to go to pause state when there is no
internet connection. If internet connection gets available it should
resume its working.
What I done so far is if I run application it starts downloading data from
remote site. If I disconnects internet connection it behaves correctly by
displaying appropriate info. But as soon as network connection is up it
resumes and only download data for one iteration of while loop.
Here is the code:
class Program
{
static bool networkIsAvailable = false;
static StreamWriter writer = null;
static int i = 1;
static string URI = "http://xxxxxxxxxxxxxxxxxxxxxxxxxxx/" + i + "/";
static void Main(string[] args)
{
writer = new StreamWriter("c:\\StudentsList.txt", true);
NetworkChange.NetworkAvailabilityChanged += new
NetworkAvailabilityChangedEventHandler(NetworkChange_NetworkAvailabilityChanged);
NetworkInterface[] nics = NetworkInterface.GetAllNetworkInterfaces();
foreach (NetworkInterface nic in nics)
{
if (
(nic.NetworkInterfaceType != NetworkInterfaceType.Loopback
&& nic.NetworkInterfaceType !=
NetworkInterfaceType.Tunnel) &&
nic.OperationalStatus == OperationalStatus.Up)
{
networkIsAvailable = true;
}
}
if (!networkIsAvailable)
Console.WriteLine("Internet connection not available! We
resume as soon as network is available...");
else
ConnectToPUServer();
}
public static void ConnectToPUServer()
{
var client = new WebClient();
while (i < 500 && networkIsAvailable)
{
string html = client.DownloadString(URI);
//some data processing
Console.WriteLine(i);
i++;
URI = "http://xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/" + i + "/";
}
}
static void NetworkChange_NetworkAvailabilityChanged(object sender,
NetworkAvailabilityEventArgs e)
{
networkIsAvailable = e.IsAvailable;
if (!networkIsAvailable)
Console.WriteLine("Internet connection not available! We
resume as soon as network is available...");
while (!networkIsAvailable)
{
//waiting for internet connection
}
ConnectToPUServer();
Console.WriteLine("Complete.");
writer.Close();
}
}
After resuming, why while loop of ConnectToPUServer is executing only once??
Thanks.