How to Troubleshoot WiFi Connection Issues in Debian 12 Bookworm

Wireless network connectivity issues can be frustrating, especially when using a Linux-based operating system such as Debian 12 (Bookworm). Whether your WiFi is not detecting networks, failing to connect, or experiencing slow speeds, this guide will walk you through various troubleshooting steps to diagnose and resolve WiFi problems effectively.

1. Check Basic Connectivity

Before diving into advanced troubleshooting, start with the basics:

• Ensure that WiFi is enabled on your system.
• Verify that the WiFi router is working correctly and broadcasting the signal.
• Check if other devices can connect to the WiFi network.
• Restart both your computer and the router to rule out temporary issues.

You can also check WiFi connectivity by running:

nmcli radio wifi

If the output is “disabled,” enable it with:

nmcli radio wifi on

2. Identify Your Wireless Interface

Run the following command to list available network interfaces:

ip link show

Look for a wireless interface, typically named wlan0 or wlp*. Alternatively, you can use:

nmcli device

This command lists all network interfaces and their states.

3. Check if the WiFi Adapter is Recognized

Sometimes, Debian may not recognize your wireless adapter due to missing drivers. Run:

lspci | grep -i wireless

Or, for USB adapters:

lsusb

If your adapter is missing from the output, it may not be properly connected or supported.

You can also check for the wireless kernel module:

lsmod | grep iwlwifi  # For Intel WiFi adapters
lsmod | grep ath9k    # For Atheros WiFi adapters

If the output is empty, the necessary driver may not be loaded.

4. Install Missing Firmware and Drivers

If Debian lacks the appropriate WiFi drivers, install them using:

sudo apt update
sudo apt install firmware-iwlwifi

For Realtek adapters:

sudo apt install firmware-realtek

After installing the drivers, reboot your system:

sudo reboot

5. Check NetworkManager Status

Debian uses NetworkManager for network management. Ensure that it’s running:

systemctl status NetworkManager

If it’s not running, start it with:

sudo systemctl start NetworkManager

To enable it at boot:

sudo systemctl enable NetworkManager

6. Restart Networking Services

Sometimes, restarting networking services can resolve WiFi problems:

sudo systemctl restart networking
sudo systemctl restart NetworkManager

7. Check Network Configuration

Incorrect configurations can prevent your WiFi from working. Check:

cat /etc/network/interfaces

If the file contains entries like iface wlan0 inet dhcp, remove them to allow NetworkManager to manage the connection.

Check active connections with:

nmcli connection show

To delete and reconnect:

nmcli connection delete <WiFi-SSID>
nmcli device wifi connect <WiFi-SSID> password <WiFi-password>

8. Analyze Log Files for Errors

System logs often provide clues to connectivity issues:

sudo journalctl -u NetworkManager --since "1 hour ago"

Look for error messages related to WiFi connectivity.

You can also check the kernel log:

dmesg | grep -i wlan

9. Manually Connect to WiFi Using iw and wpa_supplicant

If NetworkManager fails, try connecting manually:

sudo ip link set wlan0 up
sudo iw dev wlan0 scan | grep SSID

Create a WPA supplicant configuration file:

wpa_passphrase "YourSSID" "YourPassword" | sudo tee /etc/wpa_supplicant/wpa_supplicant.conf

Connect using:

sudo wpa_supplicant -B -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf
sudo dhclient wlan0

If this works, the issue may be with NetworkManager.

10. Fix Slow or Unstable WiFi

If you experience slow speeds, check signal strength:

nmcli device wifi list

To force a specific WiFi band (e.g., 5GHz), edit:

sudo nano /etc/NetworkManager/conf.d/wifi_scan-rand-mac.conf

Add:

[device]
wifi.scan-rand-mac-address=no

Then restart NetworkManager:

sudo systemctl restart NetworkManager

11. Disable Power Management for WiFi Adapter

Some network cards automatically enter power-saving mode, causing disconnects. Disable power management:

echo "options iwlwifi power_save=0" | sudo tee /etc/modprobe.d/iwlwifi.conf
sudo systemctl restart NetworkManager

12. Reset Network Settings

If none of the above works, reset network settings:

sudo rm -rf /etc/NetworkManager/system-connections/*
sudo systemctl restart NetworkManager

Then reconnect to WiFi:

nmcli device wifi connect <WiFi-SSID> password <WiFi-password>

Conclusion

Troubleshooting WiFi issues in Debian 12 Bookworm requires a systematic approach, from checking hardware compatibility and drivers to analyzing system logs and resetting network configurations. By following the steps in this guide, you should be able to diagnose and resolve most common WiFi problems efficiently.

If the issue persists, consider checking the Debian forums or submitting a bug report to the developers. Good luck with your Debian 12 system!