Type in terminal:
sudo update-initramfs -u
Provide the result of this command and I can help.
The dafault way is to:
sudo mkdir /home/username/Downloads/rtl
Elementary was originally based on Ubuntu, which was originally based on Debian.
You can set a static IP via the Network settings GUI.
Click Applications menu.
Click System Settings from the menu.
Click Network from the settings app.
Select your network connection in left-hand sidebar.
Click Advanced Settings in the lower-right corner.
Click the IPv4 ...