Fixing problem with missing wifi adapter on Ubuntu 18.04

I have installed Ubuntu 18.04 and faced a problem with WiFi adapter: in Settings in section Wi-Fi I saw a message “No WiFi Adapter Found”.

Firstly install the building tools first via command:

sudo apt-get install linux-headers-$(uname -r) build-essential git

get the newest Realtek rtlwifi codes

git clone https://github.com/lwfinger/rtlwifi_new.git

And then check out extended branch for rtl8822be or rtl8723de:

cd rtlwifi_new/ && git checkout origin/extended -b extended

install the drivers via command:

sudo make install

Once that’s done run commands load the new driver:

sudo modprobe -r rtl8723de
sudo modprobe rtl8723de

Second command has failed with error

modprobe: ERROR: could not insert 'rtl8723de': Operation not permitted

After few hours exploring internet I have found that it’s caused by UEFI Secure Boot (more here) which doesn’t allow to load third party modules. The solution is to disabled the Secure Boot.

Firstly check if SecureBoot is enabled on Ubuntu. Install mokutil

sudo apt-get install mokutil

and check the status of SecureBoot

mokutil --sb-state

In case it is enabled run command

sudo mokutil — disable-validation

Now enter a temporary password between 8 to 16 digits. We will use this password later. Enter the same password again to confirm. Once it’s done reboot the system and press any key when you see the blue screen (MOK management). Select Change Secure Boot state.

Enter the password you had selected before and press Enter.

Select Yes to disable Secure Boot in shim-signed.

Press Enter key to finish the whole procedure. That’s all.