No WiFi Adaptor found in Lenovo X1 Carbon Generation 7

We see that your system loaded firmware version -43 and it crashed. This bug report suggests that firmware version -46 will rectify the issue: https://bugs.launchpad.net/ubuntu/+source/linux-firmware/+bug/1828133

The -46 version is now included in the latest linux-firmware package. Please download this package on another computer and transfer it to the Ubuntu computer. http://security.ubuntu.com/ubuntu/pool/main/l/linux-firmware/linux-firmware_1.183.2_all.deb For convenience, please drag and drop it to the desktop of the Ubuntu computer.

Now open a terminal and do:

cd "$(xdg-user-dir DESKTOP)"
sudo dpkg -i linux*.deb

Reboot and show us:

dmesg | grep iwl

You can fix this bug by updating your system. Connect to the Internet by wire and run:

sudo apt update
sudo apt upgrade

After the process is finished, reboot and Wi-Fi should work.

The linux-firmware will be updated to a working version.

If it is difficult to update the system without a wireless connection, then download http://mirrors.kernel.org/ubuntu/pool/main/l/linux-firmware/linux-firmware_1.173.12_all.deb, copy it to your Desktop and run:

sudo apt remove linux-firmware
cd "$(xdg-user-dir DESKTOP)"
sudo dpkg -i linux-firmware_1.173.12_all.deb

I wasn't able to get wifi working on a clean install of 18.04 on my X1C7 using any combination of the steps above, however this (copied from here: https://ubuntuforums.org/showthread.php?t=2400595) did the trick

sudo apt install git build-essential
git clone https://git.kernel.org/pub/scm/linux/kernel/git/iwlwifi/backport-iwlwifi.git
cd backport-iwlwifi
make defconfig-iwlwifi-public
sed -i 's/CPTCFG_IWLMVM_VENDOR_CMDS=y/# CPTCFG_IWLMVM_VENDOR_CMDS is not set/' .config
make -j4
sudo make install
cd /lib/firmware
sudo wget https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/iwlwifi-9000-pu-b0-jf-b0-38.ucode
sudo wget https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/iwlwifi-9260-th-b0-jf-b0-38.ucode

In my case, oem kernel was worked.

sudo apt install linux-oem-osp1 linux-firmware
sudo reboot

(https://forums.lenovo.com/t5/Ubuntu/thinkpad-notebook-p1-gen-2-ubuntu-18-04-support-wireless-no-wifi/td-p/4529460)