Study ALL possible solutions but none works. I download packages and drivers to my mobile phone and transfer them to my laptop. I'm very frustrated. Can anybody help me? Thanks.
EDIT 1: Thank you Pilot6 for you answer. This is some results:
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.4 LTS
Release: 18.04
Codename: bionic
$ sudo lshw -c network
*-network UNCLAIMED
description: Ethernet controller
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:02:00.0
version: 15
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix cap_list
configuration: latency=0
resources: ioport:e000(size=256) memory:fea04000-fea04fff memory:fea00000-fea03fff
*-network UNCLAIMED
description: Network controller
product: Realtek Semiconductor Co., Ltd.
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:03:00.0
version: 00
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress cap_list
configuration: latency=0
resources: ioport:d000(size=256) memory:fe900000-fe90ffff
$ sudo modprobe rtl8723
modprobe: FATAL: Module rtl8723 not found in directory /lib/modules/5.3.0-40-generic
$ lspci | grep -i realtek
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 15)
03:00.0 Network controller: Realtek Semiconductor Co., Ltd. Device d723
I tried the following: 1) lwfinger/rtlwifi_new github's package 2) mrizkimaulidan/rtlwifi_new github's package 2) smlinux github's package 3) fintecheando github's package 4) tomaspinho/rtl8821ce github's package And so on.
EDIT2: Thank you again Pilot6. The solution of your link not resolve my problem. It's the result of your request:
$ lspci -knn | grep Net -A3
03:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:d723]
Subsystem: Hewlett-Packard Company Device [103c:8319]
Kernel modules: rtl8723de, 8723de
$ rfkill list
0: hci0: Bluetooth
Soft blocked: no
Hard blocked: no
rtl8723de
wireless device. So installing Intel drivers, or some other crap couldn't help.rtlwifi_new
askubuntu.com/a/1018851/167850 What's wrong with that? Please edit your question and add output oflspci -knn | grep Net -A3; rfkill list
terminal command.