I use the following to check to see if my user has network access which may get you the answer you are looking for.
Private Sub CheckMode()
If Application.Current.IsRunningOutOfBrowser Then
currentMode.Text = "Operating Mode: Out of Browser"
Else
currentMode.Text = "Operating Mode: In Browser"
End If
currentMode.Foreground = New SolidColorBrush(Colors.White)
End Sub
Private Sub UpdateNetworkIndicator(ByVal sender As Object, ByVal e As System.EventArgs)
If WebContext.Current.User.IsAuthenticated Then
If NetworkInterface.GetIsNetworkAvailable Then
connectionStatus.Text = "Network Status: Connected"
connectionStatus.Foreground = New SolidColorBrush(Colors.Green)
Else
connectionStatus.Text = "Network Status: Disonnected"
connectionStatus.Foreground = New SolidColorBrush(Colors.Red)
End If
End If
End Sub