How to solve Wi-Fi unavailable in Linux Mint on Dell Latitude notebook

Written by Claudio Kuenzler - 0 comments

Published on August 15th 2023 - Listed in Linux Hardware

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Today I ran into a typical "head scratcher", where you can't see the forest for the trees. I am so used to dig deep into a technical problem, that the most obvious solution didn't even cross my mind (at first).

No Wireless LAN: Wi-Fi unavailable

I needed to check a document on my Dell Latitude E7440 notebook, which I haven't touched for the last couple of days (I usually work on a desktop computer) when I noticed that I had no Internet connection. Wi-Fi turned off, I thought. That's what I sometimes do when I use a wired connection. But to my big surprise the Network Connection manager in Linux Mint (21) showed me that Wi-Fi is unavailable:

A toggle of the button did not work. This usually enabled the Wi-Fi / WLAN interface and therefore the connection again.

Wireless LAN hard blocked

Many results can be found when searching for "mint wifi unavailable" or a similar key phrase. In general, most (technically good) hints use the command inxi and rfkill to show advanced information on the wireless controller.

The basic inxi output shows the wireless lan controller is in state down:

ck@mint:~$ inxi -nn
Network:
  Device-1: Intel Ethernet I218-LM driver: e1000e
  IF: eno1 state: down mac: xx:xx:xx:xx:xx:xx
  Device-2: Intel Wireless 7260 driver: iwlwifi
  IF: wlp2s0 state: down mac: xx:xx:xx:xx:xx:xx
  IF-ID-1: vmnet1 state: unknown speed: N/A duplex: N/A
    mac: 00:50:56:c0:00:01
  IF-ID-2: vmnet8 state: unknown speed: N/A duplex: N/A
    mac: 00:50:56:c0:00:08
  IF-ID-3: wwan0 state: down mac: f2:bc:6a:af:b9:c3

But the reason is not shown. The rfkill command output shows something interesting though:

ck@mint:~$ rfkill list all
1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes
2: dell-wifi: Wireless LAN
    Soft blocked: no
    Hard blocked: yes
3: dell-bluetooth: Bluetooth
    Soft blocked: no
    Hard blocked: yes
4: dell-wwan: Wireless WAN
    Soft blocked: no
    Hard blocked: yes
5: nfc0: NFC
    Soft blocked: no
    Hard blocked: no

All the wireless related adapters (including Bluetooth) are set to hard blocked. According to a related question on Ask Ubuntu, rfkill is able to unblock all or certain adapters:

ck@mint:~$ rfkill unblock all

But this only works for "soft blocked" entries and has no effect on hard blocked adapters:

ck@mint:~$ rfkill list all
1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: yes
2: dell-wifi: Wireless LAN
    Soft blocked: no
    Hard blocked: yes
3: dell-bluetooth: Bluetooth
    Soft blocked: no
    Hard blocked: yes
4: dell-wwan: Wireless WAN
    Soft blocked: no
    Hard blocked: yes
5: nfc0: NFC
    Soft blocked: no
    Hard blocked: no 

Physically blocked by the hardware toggle

The important hint from AskUbuntu user Lekensteyn for "hard blocked" entries is the following:

"Hard blocked" cannot be changed by software, look for a wifi toggle on your keyboard or edges of the laptop; the device can also be hard blocked if disabled in the bios.

I was confident that I did not change the BIOS settings (in many years) so maybe I accidentally hit a magic combo on the keyboard? However on that Dell Latitude E7440, there is no FN-combo for toggling Wi-Fi.

Then I remembered: There's a switch on the right edge of the notebook!

Could this be it? Could I have accidentally toggled that switch the last time I moved my notebook? Let's try and toggle it to the other direction, so the "red background" is hidden.

And almost immediately, the Wireless LAN connection was established. rfkill now shows a different output, too:

ck@mint:~$ rfkill list all
1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no
2: dell-wifi: Wireless LAN
    Soft blocked: no
    Hard blocked: no
3: dell-bluetooth: Bluetooth
    Soft blocked: no
    Hard blocked: no
4: dell-wwan: Wireless WAN
    Soft blocked: no
    Hard blocked: no
5: nfc0: NFC
    Soft blocked: no
    Hard blocked: no
6: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no

Any normal user would have probably tried that first and would have solved that faster than me. Sometimes it helps to take a step back to "see the forest" again - quite literally in this case.

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