I downloaded and installed your firmware version 18.06.2 on a Linksys WRT1900ACV1. Now I am trying to install support for NTFS, but the console answers for packages: kmod-fs-ntfs and ntfs-3g:
Unknow package 'name-package'
opkg_install_cmd: Cannot install package name-package
Can you tell advice me, on how to install these packages. Also I want to share this external disk in my local network.
or updating the package list and installing them through LuCI?
The package lists are kept on a RAM-backed temporary file system, so they need to be fetched (opkg update) before they have any content after every boot. It's a good idea to fetch them before any install.
You may need some other packages to get the WRT1900 to recognize USB storage, but I don't know that unit well enough to know what is already installed.