Device Not Responding to Ping? Why It Can Still Be Online

The printer prints, the NAS share opens, the doorbell just sent a notification. And yet a ping gets no reply, or the device is missing from a network scan. Is the scan wrong, or is the device gone? In this video we'll look at what a missing reply really means, and how to check it without switching off any protection.

As always, this is DeviceShelf's demo network, a made-up home with forty-four devices.

A ping sends one small message, an echo request, and waits for the echo. The Ping column shows how long that took. But nothing obliges a device to answer. Out of the box, Windows only answers a ping once file and printer sharing is switched on. Many cameras, phones and smart plugs ignore it, and a phone in standby answers nothing at all. So a missing reply is one observation about one kind of request, not a verdict on the device.

The reverse is true as well. A device that answers a ping can still have a broken service. The printer replies, and printing fails anyway.

That's why a good scan doesn't rely on ping alone. DeviceShelf also asks for every address on the local network through A R P, the address lookup that every device has to answer to talk on the network at all. It listens for Bonjour and U P n P announcements, and it reads names from the network. A device that ignores ping still shows up, as long as it's awake and on the same network.

Here is a device that answers nothing. A battery doorbell sleeps between rings to save power, so the response time stays empty. It's online all the same. DeviceShelf knows it's there because the router reports it in its list of connected devices.

That's this setting: Settings, Scanning, Router or controller. Connect your router here, and DeviceShelf adds the devices the router knows but the scan didn't reach, sleeping devices included. It also shows for every device how it got its address.

Sleep is one reason. The other common one is location. Is the device on the same network as the computer that scans? A guest Wi-Fi or a separate network for smart home gear usually blocks traffic between devices on purpose. And a scan of one nine two, one six eight, one, dot zero, slash twenty-four doesn't include a device at one nine two, one six eight, one sixty-eight, dot twenty-five, even if both sit in the same house. The Network view shows which range this computer is on.

For devices in another range that you manage, SNMP discovery reads the address tables of your routers and switches and adds what they know. What you shouldn't do is switch off guest isolation just to make a device show up in a scan. That protection is usually there for a reason.

When a device is missing, compare like with like. Run the scan again from the same computer, on the same network, a minute later. If the device is there now, it was probably asleep or busy. If it's still missing, check the router's list of connected devices next. Is the device listed there with a current lease, or only as an old entry from yesterday? A router's list mixes both, and only the current one tells you the device is on the network right now.

A single missed reply shouldn't raise an alarm. Under Settings, Alerts, you choose when a device counts as offline. The standard setting waits for three missed checks in a row. Tolerant waits for six, which suits phones and battery devices that nap a lot. And you can wait a few minutes before an alert goes out.

When you're not sure, check the service you actually care about. For a printer, open its web page. For a NAS, open the share. That tells you more than any ping. Don't turn off a device's firewall to test a scan. Allowing ping is a choice about what the device reveals, and the device works fine without it.

And keep the details when something looks odd: the time, which computer scanned, which network it was on, and what you checked. A note like, the printer was reachable through its web page but didn't answer the scan, is more useful than marking it offline.

Over time, the history in a device's details tells you how it usually behaves. This Raspberry Pi was reachable about ninety-seven percent of the time over the last day, with one outage you can open and look at. A device that drops off every night at the same time is probably on a timer or in a power saving mode, not broken.

So: no reply to a ping doesn't mean a device is gone. Scan with more than ping, connect your router for the sleeping devices, check whether the device is on the same network, and test the service you need before you change any security setting.

More videos about your home network are on our channel. DeviceShelf runs on Mac, Windows and Linux, at deviceshelf dot app.