Unable to install Realtek rtl8723de drivers? (networking)
If you reinstall 18.04, which uses kernel version 4.15-xx, then the step-by-step instructions will differ from this answer. This answer assumes that you remain with 19.04 using kernel version 5.0-xx:
git clone https://github.com/smlinux/rtl8723de.git -b 5.0-up
sudo dkms add ./rtl8723de
sudo dkms install rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414
sudo depmod -a
Reboot.