Sorry I did not get enough information what is a manual upgrade.
You do not need to use fvdw-sl console but still the firmware menu with a user action. It is the user which provides the upgrade package and not the firmware which downloads itself the latest update package.
So with a manual upgrade, the user can either downgrade the firmware version or use the latest version.
Then to install version 17.0, download the packages for version 17.0 (rar files), extract its zip file. Upload the zip and run the manual upgrade like described here :
https://plugout.net/viewtopic.php?f=7&t=3059#p38736