Pinging many devices at same time cause a timeout? - wpf

Question

Similar to other ping questions here, we need to ping many IP addresses at the same time. We thought we had it running great after following many responses and examples from here, however we are experiencing failed pings due to timeout when we attempt to ping them at the same time, or even close together.
We tested our list of IP's on another ping monitoring program and the timeout does not happen. The issue is specific to our application.
In our application, every "device" has a RouterProperties class that holds its Name, IP Address, etc. We ping from the observable collection of these devices, getting their IP addresses from their RouterProperties.
Tested separating pings by 10(ms)/20(ms) await task.delay
Tested separating pings by 10(ms)/20(ms) using a dispatcher timer
Tested pinging all at once with no delay between, causing largest amounts of timeouts.
Tested converting IP Address "strings" to IP Address before pinging, no visible change in issue.
Tested with ping timeout at 500(ms), 1000(ms), 5000(ms), etc.
Current test is for 143 devices, but needs to be able to handle more.
//OUR MAIN PING SCHEDULER
private async void PingAllDevices(object sender, EventArgs e)
{
var allPingTasks = new List<Task>();
int numOfDevices = 1;
//Assign a task to each device.
foreach (RouterProperties device in devices)
{
await Task.Delay(10);
Console.WriteLine("Pinging device #" + numOfDevices + " : " + device.RouterIP);
numOfDevices++;
allPingTasks.Add(AsyncPingDevice(device));
}
//Block here for all created tasks.
await Task.WhenAll(allPingTasks);
}
}
//OUR PING TASK
async Task AsyncPingDevice(RouterProperties device)
{
// Get device IP address to ping.
string deviceIP = device.RouterIP;
try
{
Ping pingSender = new Ping();
PingOptions options = new PingOptions();
var reply = await pingSender.SendPingAsync(deviceIP, (int.Parse(Properties.Settings.Default.PingTimeout)), buffer, pingOptions);
Console.WriteLine(deviceIP + " has responded.");
if (reply.Status == IPStatus.Success)
{
device.PingCounter = 0;
}
else
{
if (device.PingCounter <= 3)
{
device.PingCounter++;
}
}
}
catch
{
if (device.PingCounter <= 3)
{
device.PingCounter++;
}
}
await Dispatcher.BeginInvoke(DispatcherPriority.Normal, new Action( () =>
{
if (device.IsDeactivated != true)
{
switch (device.PingCounter)
{
case 0:
device.Color = "#FF8AA587";
break;
case 1:
device.Color = "#FF9AB999";
break;
case 2:
device.Color = "#FFFCCEAA";
break;
case 3:
device.Color = "#FFF4837D";
break;
case 4:
device.Color = "#FFEB4960";
break;
}
}
}));
}
When we run our code, with and without the task.delay inside the ping scheduler to separate the pings, we end up with inconsistent results from the devices being pinged.
Without the delay = 75% of all devices timeout.
With the delay = inconsistently random 10% of devices timing out per
cycle.
Similar ping program to ours = 100% consistent results without any
timeouts.