Yes. It is available to me anytime I have an internet connection through the dynamic DNS provided by Synology. It looks something like yourname.synology.me.
I use Synology apps on my NAS to handle contacts, calendar and file syncing. One of these days I’ll be completely off of Google. I also have SFTP running on my NAS so I can back websites up off my web server saving drive space there where it’s expensive.