In this article you will learn, how to check Internet connection availability, Internet connection availability via WWLA(WiFi) or WWAN (Mobile), check whether device connected to a metered network or not and sense the significant network availability changes.

1. Check Internet Connection Availability

To check whether internet connected or not use GetIsNetworkAvailable method of NetworkInterface class.

bool isInternetConnected = NetworkInterface.GetIsNetworkAvailable();

GetIsNetworkAvailable() -
Summary: Indicates whether any network connection is available.
Returns: true if a network connection is available; otherwise, false.


2. Check Internet Connection Availability via WWLN (WiFi)

To check whether internet connected via WWAN use IsWlanConnectionProfile property of ConnectionProfile class

ConnectionProfile InternetConnectionProfile = NetworkInformation.GetInternetConnectionProfile();
bool isWLANConnection = (InternetConnectionProfile == null)?false:InternetConnectionProfile.IsWlanConnectionProfile;

IsWlanConnectionProfile
Summary: Gets a value that indicates if connection profile is a WLAN (WiFi) connection. This determines whether or not WlanConnectionProfileDetails is null.
Returns: Indicates if the connection profile represents a WLAN (WiFi) connection.


3. Check Internet Connection Availability via WWAN (Mobile)

To check whether internet connected via WWAN use IsWwanConnectionProfile property ofConnectionProfile class

ConnectionProfile InternetConnectionProfile = NetworkInformation.GetInternetConnectionProfile();
bool isWLANConnection = (InternetConnectionProfile == null)?false:InternetConnectionProfile.IsWwanConnectionProfile;

IsWwanConnectionProfile
Summary: Gets a value that indicates if connection profile is a WWAN (mobile) connection. This determines whether or not WwanConnectionProfileDetails is null.
Returns: Indicates if the connection profile represents a WWAN (mobile) connection.


4. Check Metered network

To check whether Internet reachable via a metered connection or not, use GetConnectionCost method on NetworkInterface class.

var connectionCost = NetworkInformation.GetInternetConnectionProfile().GetConnectionCost();
if (connectionCost.NetworkCostType == NetworkCostType.Unknown 
        || connectionCost.NetworkCostType == NetworkCostType.Unrestricted)
{
    //Connection cost is unknown/unrestricted
}
else
{
   //Metered Network
}

Reference (More detailed answer)
1. https://msdn.microsoft.com/en-us/library/windows/apps/xaml/JJ835821(v=win.10).aspx
2. https://msdn.microsoft.com/en-us/library/windows/apps/xaml/windows.networking.connectivity.networkcosttype.aspx


5. Manage network availability changes

To sense the significant network availability changes, use eventNetworkStatusChanged of NetworkInformation class

// register for network status change notifications
 networkStatusCallback = new NetworkStatusChangedEventHandler(OnNetworkStatusChange);
 if (!registeredNetworkStatusNotif)
 {
     NetworkInformation.NetworkStatusChanged += networkStatusCallback;
     registeredNetworkStatusNotif = true;
 }

async void OnNetworkStatusChange(object sender)
{
    // get the ConnectionProfile that is currently used to connect to the Internet                
    ConnectionProfile InternetConnectionProfile = NetworkInformation.GetInternetConnectionProfile();

    if (InternetConnectionProfile == null)
    {
        await _cd.RunAsync(CoreDispatcherPriority.Normal, () =>
        {
            rootPage.NotifyUser("Not connected to Internet\n", NotifyType.StatusMessage);
        });
    }
    else
    {
        connectionProfileInfo = GetConnectionProfile(InternetConnectionProfile);
        await _cd.RunAsync(CoreDispatcherPriority.Normal, () =>
        {
            rootPage.NotifyUser(connectionProfileInfo, NotifyType.StatusMessage);
        });
    }
    internetProfileInfo = "";
}

References
1. https://msdn.microsoft.com/en-us/library/windows/apps/xaml/jj835820.aspx
2. https://msdn.microsoft.com/en-us/library/windows/apps/xaml/hh452991.aspx