With a temporary working internet connection by ethernet, tethered or any other means, open a terminal Ctrl+Alt+t and do:
sudo apt update
sudo apt install build-essential git dkms
git clone https://github.com/tomaspinho/rtl8821ce.git
cd rtl8821ce
sudo ./dkms-install.sh
The file builds for me on my 18.04 system with a few possibly harmless warnings but no errors.
Follow with:
sudo modprobe 8821ce
You should be all set.
Ubuntu does not have pre-installed drivers for Realtek Hardware. You were lucky that your wifi worked fine, because I had suffered about almost a month repairing the wifi issues. Now let's solve the realtek problem:
First ensure that you are having Linux kernel > 4.14. To check that, type following on terminal:
uname -msr
If you get something like Linux 4.15, assume everything is fine. And just in case if its not higher than 4.14 (since you are using Ubuntu 18.04, by default the Linux kernel which comes in package is 4.15, so this is for the ones who are still at Ubuntu 16.04), Connect to Ethernet and type following commands:
sudo -s
sudo apt-get dist-upgrade
sudo apt-get upgrade
sudo apt-get update
reboot
This will take time, but have patience. By now you should have linux kernel > 4.14. Now comes the real driver installation part.
Ensure you have installed git. If not type the following command:
sudo apt-get install git
git clone https://github.com/tomaspinho/rtl8821ce.git
cd rtl8821ce/
sudo make all
sudo make install
sudo modprobe -a 8821ce
reboot
This should solve your problem.
Best Answer
Update: as of 14.10 utopic, there is a semi-working driver included by default, but it frequently disconnects and has difficulty reconnecting. The best solution is to continue to build the lwfinger driver as described below and then blacklist the driver included in Ubuntu.
That how-to link is outdated; the latest version of the rtl8723au wireless driver can be found at https://github.com/lwfinger/rtl8723au.
In preparation we'll need some build tools and kernel headers:
Here are the steps to install:
When you update the kernel, you'll need to run these steps again to get wireless working (except for the
git clone). To fetch the latest version of the code, usegit pull. Alternatively you can set up DKMS to do that for you as described in user20826's answer.The bluetooth driver for that chip can then be found at https://github.com/lwfinger/rtl8723au_bt. Perform the preparation as above and install like this: