Solution for case if rtl8723de doesn't work or works but has weak signal.
at first download an unpack from one of this places: https://github.com/jeremyb31/rtl8723de https://github.com/georgydunaev/rtl8723de https://github.com/smlinux/rtl8723de
sudo dkms add ./rtl8723de fix osdep_service_linux.h as it told in wifi.txt add this to Makefile in /usr/src/ OR in sudo gedit /var/lib/dkms/rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414/source/Makefile (if you already done: )
EXTRA_CFLAGS += -Wno-date-time EXTRA_CFLAGS += -Wno-incompatible-pointer-types
Then: sudo dkms install rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414
Then reboot.