wifi_adapter.md

When an Ubuntu Wi-Fi adapter is detected (seen by the system) but is "down" or disconnected, it usually indicates a driver issue, power management conflict, or that the Network Manager service needs to be restarted.

Here are the most effective solutions, ordered from simplest to most advanced:

1. Restart Network Manager Often, the network management service has simply crashed or frozen.

$ sudo systemctl restart NetworkManager

If you are using a USB adapter, unplug it and plug it back in after running this command

2. Bring the Interface Up Manually

If the adapter is listed but not active, you can force it up. Find your interface name (e.g., wlan0, wlp3s0):

$ ip link show

Bring it up:

$ sudo ip link set <interface_name> up

Alternatively, try: sudo ifconfig <interface_name> up.

3. Check for Hardware/Software Switches (Airplane Mode)

Your Wi-Fi might be blocked by a physical switch on the laptop or by software (RF-Kill). Check for blocks:

$ rfkill list

If it says "Hard blocked" or "Soft blocked", unlock it:

$ sudo rfkill unblock wifi

Ensure your laptop's WiFi function key (e.g., Fn+F2) hasn't disabled the card.

4. Reinstall/Update Drivers (If "Additional Drivers" lists options)

If lsusb or lspci shows the device but it doesn't work, you may need restricted drivers. Open Software & Updates. Go to the Additional Drivers tab. If a driver is listed for your wireless card, select it and click Apply Changes.

5. Disable Power Saving

Sometimes the Wi-Fi card powers down to save energy and fails to wake up. Edit the NetworkManager configuration:

$ sudo nano /etc/NetworkManager/conf.d/default-wifi-powersave-on.conf

Change wifi.powersave = 3 to wifi.powersave = 2 (2 means disabled). Save, exit (Ctrl+O, Enter, Ctrl+X), and restart the service: sudo systemctl restart NetworkManager.

6. Power Cycle (Hard Shutdown)

If you dual-boot with Windows or recently had a kernel update, the card might be in a weird state. Shut down the computer completely. Unplug the power cable and remove the battery (if possible). Hold the power button for 30 seconds.

7. Reinstall Kernel Modules

If the driver is corrupted, reinstalling the firmware modules can fix it.

$ sudo apt install --reinstall linux-firmware
$ sudo apt install --reinstall linux-modules-extra-$(uname -r)

Then reboot.

Need to know the specific model? Run this command to see what driver your device is currently using:

$ lspci -nnk | grep -iA3 net