You want some privacy on the internet highway for outbound connections of your nas. The reasons can be varied. Some want to just have some privacy.
Some want to download the movies and series they can not get legally. Some want to test stuff with different IP addresses. Lots of reasons out there
This article explains how you can make this happen on a Synology Nas and the reason why
this solution was chosen above other possible solutions…
Be warned! This is a very technical article and not for the faint of heart :-)