No wifi detected on lenovo thinkpad t14.s

Based on the computer's specs pdf given here, you have one of the modern Wifi cards such as

• Intel Wi-Fi® 6 AX200, 802.11ax 2x2 Wi-Fi + Bluetooth 5.2
• Intel Wi-Fi 6 AX201, 802.11ax 2x2 Wi-Fi + Bluetooth 5.2
• Intel Wi-Fi 6E AX210, 802.11ax 2x2 Wi-Fi + Bluetooth 5.2

and the issue might be about your kernel version. For example if you have (Intel Wi-Fi® 6E AX210) it requires at least kernel version 5.10 and can verify this at here. Please check your kernel version with uname -a command.

As stated in one of the answers in this link, "The Linux 5.10 kernel (or later) will ship as part of Ubuntu 21.04 in April. This version will also get backported to Ubuntu 20.04 LTS at a later date. It's possible to manually install a mainline kernel in Ubuntu however if it breaks you get the pieces." You can install kernel 5.11 to make the wifi adapter work, but as suggested in the same answer be warned to review the implications of installing a kernel version manually here.

Installing Kernel 5.11

• First install Mainline as a graphical kernel installing tool. (See details here)
• run sudo add-apt-repository ppa:cappelikan/ppa
• sudo apt update
• sudo apt install mainline
• Open Mainline Kernel Installer and install 5.11.0
• After installation, reboot.
• sudo update-grub and sudo reboot
• As described here, the output of sudo dmesg | grep iwl will show us some errors with the information about which firmware we need to install.
• For example you might need iwlwifi-ty-a0-gf-a0-39 to iwlwifi-ty-a0-gf-a0-59.

Installing Firmware

• At the output of dmesg command it is suggested to check https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/
• Go this website and download the newest firmware (eg. as of today it was linux-firmware-20211027.tar.gz (sig))
• It takes some time to download, be patient
• Uncompress the file with tar -zxvf linux-firmware-20211027.tar.gz
• cd linux-firmware-20211027/
• Copy the firmwares to /lib/firmware/ with command sudo cp -ax * /lib/firmware
• Now reboot and the wifi should work!