How to fix issues with realtek wifi card rtl8821ae on Ubuntu - at least is how I fixed it
1 - Upgrade to Ubuntu 18.04.1
2 - Follow the tutorial at https://github.com/lwfinger/rtlwifi_new/blob/master/README.md
3 - Reboot your computer
4 - Open terminal and type "sudo iwconfig wlp3s0 power off" to disable power management
5 - Type "sudo nano /etc/NetworkManager/conf.d/default-wifi-powersave-on.conf" on terminal, change the value from 3 to 2 and save, this will save your power management settings
6 - If only this works for you, stop here, else continue
7 - Type "sudo service network-manager restart" on terminal to restart network manager
8 - Type "sudo ip link set wlp3s0 down"
9 - Type "sudo modprobe -rv rtl8821ae"
10 - Type "sudo modprobe -v rtl8821ae swenc=Y"
11 - This should work, but when you reboot and wifi doesn't work try to type this commands on terminal:
sudo service network-manager restart
sudo ip link set wlp3s0 down
sudo modprobe -rv rtl8821ae
sudo modprobe -v rtl8821ae swenc=Y
If this does not work then you're cursed. F*ck realtek