I just installed Ubuntu 20.04 on my Lenovo Yoga 6 but I can’t connect to wifi, it just says "No Wi-Fi Adapter Found"

I can use USB tethering if there’s a solution that requires that

$ sudo lshw -C network
  *-network UNCLAIMED       
       description: Network controller
       product: Realtek Semiconductor Co., Ltd.
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:02:00.0
       version: 00
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress cap_list
       configuration: latency=0
       resources: ioport:2000(size=256) memory:c0700000-c07fffff

>Solution :

To get the Realtek PCI adapter working with Ubuntu, follow these steps:

1. Update the software cache (repository list) and install the required dependencies:

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

2. Download and install the correct drivers:

   git clone https://github.com/lwfinger/rtw89.git -b v5
   cd rtw89 && make && sudo make install
   

3. Reboot to confirm the installation:

   sudo reboot
   

4. Load the module:

   sudo modprobe rtw89pci
   

Sometimes the installation is not successful. In that case, refer to this:
https://github.com/lwfinger/rtw89#installation-instruction

If there were errors while loading the module, most probably it is due to corrupted/unsuccessful installation. Try reinstalling the drivers and rebooting.

You need to reinstall these drivers every time your kernel gets an upgrade.

1. Change the current directory to the directory we cloned earlier:

   cd rtw89
   

2. Run:

   make clean && git pull
   

3. Install the drivers:

   make && sudo make install 
   

4. Reload the drivers

   sudo modprobe rtw89pci