$($a$)$ How does SDN support intent$-$based networking? Explain the concept of decoupling in SDN$?$

$($b$)$ Reena has a Windows $8$ computer set up with IP address $192\mathrm{.}168\mathrm{.}1\mathrm{.}14$ at her home. The computer has Internet connectivity and able to browse public websites $-$ twitter.com, irctc.co$.$in$,$ etc. $$without any issues. Reena has setup a file server in the computer to upload$/$download files, which she is able to do from other computers$/$laptops at her home. Reena has shared this IP address and file server credentials to her friend Santhosh who lives in next street from her home. But Santosh is unable to access Reena's file server, from his home computer which is Ubuntu $14\mathrm{.}04,$ with IP address $192\mathrm{.}168\mathrm{.}1\mathrm{.}24.$ Reason out why this issue pops up$.$Give a possible solution for this setup to work.