The output to uname -rs is:
Linux 4.16.0-999-lowlatency
The output to iwconfig is:
enp2s0 no wireless extensions.
lo no wireless extensions.
The output to sudo modprobe 8723de is:
[sudo] password for chinodroid:
modprobe: FATAL: Module 8723de not found in directory /lib/modules/4.16.0-999-lowlatency
The rtl8723de driver is in the extended branch of lwfinger's GitHub repo. The driver will make its way into the Linux kernel supplied with Ubuntu eventually, but if you need the driver now, you can build and install it yourself.
Step 1 is to compile the WiFi drivers in lwfinger's repo. Feel free to modify the number appended to the -j flag on make to change the number of parallel build jobs to suit the system, for instance, if memory is low.
$ git clone --branch extended https://github.com/lwfinger/rtlwifi_new.git >/dev/null 2>&1
$ cd rtlwifi_new && make -j8
Step 2 is to install the driver and reboot. After the restart, the driver should load automatically, but if it doesn't, it can be manually loaded with modprobe.
$ sudo make install
$ sudo reboot
[ system reboots ]
$ lsmod |grep --quiet rtl8723de || sudo modprobe rtl8723de