Opkg_install_cmd: Cannot install package kmod-usb-storage-uas

On the wiki page "using storage devices" it was written that

For UASP driver support, install: opkg install kmod-usb-storage-uas.

When I try to install this package I get the following error:

opkg_install_cmd: Cannot install package kmod-usb-storage-uas.

The package probably does not exist (although its page does exist).
What is the meaning of this? Is it inserted into kmod-usb-storage-extras?
Maybe the package has not yet been released and will be released in the future?

The wiki link you provided seems to have moved. Is this what you were referring to:
using storage devices ?

But I also found your opkg install kmod-usb-storage-uas into this Wiki.

Anyway, I cannot find it neither in my Luci software package running LEDE 17.01.2.

Since the patch was created on Sept 23 this is likely only available in Snapshot builds or if you build your own image from trunk.

The page indeed splited. What you found is what I saw.

Currently the SMB transfer rates from the hard drive who connected to my router via USB 3.0 are pretty bad. I do not know if that will make the difference, but we'll see.