Network Troubleshooting Guide Linux
CLI diagnostic & recovery
12 structured steps — from status check to system reboot
Troubleshooting quick reference
| # | Step | Main command |
|---|---|---|
| 1 | Check network status | nmcli device status |
| 2 | Restart NetworkManager | sudo systemctl restart NetworkManager |
| 3 | Verify service is active | systemctl status NetworkManager |
| 4 | Rescan Wi-Fi | nmcli device wifi rescan |
| 5 | List available Wi-Fi | nmcli device wifi list |
| 6 | Reconnect to Wi-Fi | nmcli device wifi connect "SSID" password "PASS" |
| 7 | Restart LAN interface | sudo ip link set enp3s0 down/up |
| 8 | Renew DHCP lease | sudo dhclient -r && sudo dhclient |
| 9 | Disable airplane mode | sudo rfkill unblock all |
| 10 | Check adapter detection | lspci | grep -i network |
| 11 | Check network error logs | journalctl -u NetworkManager -n 50 |
| 12 | Reboot system | sudo reboot |
1
Check network status
nmcli device status
Displays list of network devices and their status (connected/disconnected/unavailable).
2
Restart NetworkManager
sudo systemctl restart NetworkManager
Restarts NetworkManager service to resolve temporary conflicts.
3
Verify service is active
systemctl status NetworkManager
Ensures the service is running normally (active/running).
4
Rescan Wi-Fi
nmcli device wifi rescan
Performs a fresh Wi-Fi scan (takes a few seconds).
5
List available Wi-Fi
nmcli device wifi list
Shows detected SSIDs along with signal strength.
6
Reconnect to Wi-Fi
nmcli device wifi connect "YOUR_SSID" password "YOUR_PASSWORD"
Replace YOUR_SSID and YOUR_PASSWORD with your actual network credentials.
7
Restart LAN interface
sudo ip link set enp3s0 down
sudo ip link set enp3s0 up
sudo ip link set enp3s0 up
Replace enp3s0 with your interface name (check using
ip link).8
Renew DHCP lease
sudo dhclient -r
sudo dhclient
sudo dhclient
Renews IP address from DHCP server (release and request new IP).
9
Disable airplane mode
rfkill list
sudo rfkill unblock all
sudo rfkill unblock all
Ensures airplane mode is off and all radios (Wi-Fi/Bluetooth) are active.
10
Check adapter detection
lspci | grep -i network
lsusb
lsusb
Verifies the network device is detected by the system (PCI for internal, USB for dongles).
11
Check network error logs
journalctl -u NetworkManager -n 50 --no-pager
Shows the latest 50 lines of NetworkManager logs (errors/warnings).
12
Reboot if still failing
sudo reboot
Final step if all previous methods fail to restore connectivity.
Linux Network Troubleshooting Guide | Red Edition
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