BootCamp: Can't install the software because it is not currently available from the Software Update server.
MacBook Pro with Retina display, macOS Sierra (10.12.6), null
MacBook Pro with Retina display, macOS Sierra (10.12.6), null
Sorry, but I am confused on how to use this (・_・ヾ
From Terminal, can you 'ping' swcdn.apple.com ?
As a test, can you use Brigadier - https://github.com/timsutton/brigadier - to download the software?
Download the zip file in a directory. The link has an example command line.
BootCamp: Can't install the software because it is not currently available from the Software Update server.