Today, I connected my desktop computer to the router with an ethernet cable rather than Wi-Fi due having problem with a Wi-Fi extender. But the ethernet interface doesn’t worked. The problem didn’t occurred when test it on the Windows 10. So, the problem must be on Ubuntu. I had investigate the problem for a while, then I realized that the DHCP was not working, and also “netplan” package was not installed on my system. If you don’t know about netplan, it’s a default network configuration manager on the Ubuntu which is configuring DHCP automatically.

To be sure that your problem is DHCP, your connection will be work after sending this command, and your computer will be listed on the LAN clients at the router’s administration UI.

sudo lshw -c network # Find your interface name of the ethernet adapter
sudo dhclient <ETHERNET-ADAPTER> # i.e.: enp3s0

If the connection established successfully, we can be sure that the problem is from DHCP. Let’s install and configure netplan, then reboot your system:

sudo apt-get install netplan.io
sudo netplan generate
sudo netplan apply
reboot

This problem probably occurred when netplan package was uninstalled accidently or Ubuntu was not upgraded properly. Anyway, we know how to solve this problem now.