Secure file server access from Internet

5 Ways to Access Your PC’s Files Over the Internet

You could ... set up a VPN server on your ... network and connect to that. Your computer will then be considered part of your local network, and it can access all local file shares. This allows you to access shared Windows folders and other network storage devices that would only be accessible on the local network.
This is the way businesses grant access to their file shares. Rather than securing potentially insecure file-sharing solutions, you just have to secure the VPN server itself and control access to it.
If you have already have an SSH server running on your local network, you can use SSH tunneling to access local network resources rather than setting up a VPN.

VPN vs SSH
The main difference between SSH and VPN is that VPN works on the transport level while SSH works on an application level.