DOCS: subnets

Signed-off-by: jokob-sk <jokob.sk@gmail.com>

Author: jokob-sk

docs/SUBNETS.md

@@ -8,8 +8,14 @@ You need to specify the network interface and the network mask. You can also con
 > If you don't see all expected devices run the following command in the NetAlertX container (replace the interface and ip mask):
 > `sudo arp-scan --interface=eth0 192.168.1.0/24`
 >
->  If this command returns no results, the network is not accessible due to your network or firewall restrictions (Wi-Fi Extenders, VPNs and inaccessible networks). If direct scans are not possible, check the [remote networks documentation](./REMOTE_NETWORKS.md) for workarounds.
-
+>  If this command returns no results:
+>
+> - ✅ If you see output like `IPv4: (none)` or `Using 0.0.0.0`:
+>   → The interface was not detected correctly.
+>   → Fix: explicitly set the interface using `--interface=<name>`.
+>
+> - ❌ If the scan runs correctly but still finds no devices:
+>   → The network may not be accessible due to firewall, VLAN, or network restrictions (Wi-Fi extenders, VPNs, etc.). If direct scans are not possible, check the [remote networks documentation](./REMOTE_NETWORKS.md) for workarounds.
 
 ## Example Values