Online Devices is reported Offline

[seh2000]

Hi,
Just wondering.
I see - often - that a number of devices that I know for sure are online and when comparing with devices on the cloud gateway are reported Offline (see snip below). Like the Echo it is next to me streaming music, or the NTS52 it's a LED string light which is running.
Could it be that I need to enable additional Plugins in addition to those I have enabled or is there another reason for Online devices reported Offline?
Enabled Plugins:
Unifi Import (API), PiHole (Device sync), Internet-Check, NSLOOKUP, Dig
Steen

[jokob-sk]

Hi Steen,

What you’re seeing is expected with the current set of plugins you have enabled.

None of the plugins you listed actually prove that a device is online right now:

UniFi Import (API) – reports what the UniFi controller last saw, which can lag or mark devices offline even though they’re still active.

Pi-hole (Device sync) – only shows devices that recently used DNS; a device can be online and silent.

NSLOOKUP / DIG – DNS resolution works even if the device itself is offline.

Internet-Check – verifies WAN connectivity, not individual devices.

So it’s entirely possible (and common) for devices like an Echo streaming music or an LED controller to be online but shown as offline when only these plugins are used.

If you want reliable online/offline detection, you should enable ICMP (ping).
ICMP is the only check that directly answers the question “is this device reachable on the network right now?” and is therefore the most reliable method for device status. The other plugins are best used for discovery, identification, and enrichment — not reachability.

In short:

Enable ICMP → accurate online/offline status

Keep the others → metadata, names, vendors, history

That should resolve the discrepancy you’re seeing.

Hope that clarifies it 👍

[seh2000]

@jokob-sk
Thanks for the great and easy to understand explanation on each of the plugins that I use!
Certainly, this clarifies this.
I had a suspension that I needed to use another plugin in addition to the enabled ones.
ICMP is the way - now comes the challenge to get ICMP allowed across the vlans through the firewall.
Thanks again for your great work on NetAlertX! 👏👏👏
Steen