In Windows this was the traditional way of having two networks connected by VPN before there were the modern commercial VPN "services" (forwarding services) which solve a different problem.
Often a small business would get a Firewall/VPN-Router in each location when they got broadband, and that was all that was necessary to put as an interface between each established LAN and the internet, as VPN endpoints, so you could connect offices by tunneling over the web. The routers would be programmed with the desired port forwarding, matching confidential encryption keys, and between them the router hardware alone would handle the secure VPN part of it as they communicated with each other across the web. Access to shared folders and drives was according to each separate LAN's further enablement & Windows security settings, which could sometimes be confusing, but in this case Windows does not handle the VPN itself.
Your VPN-Router/VPN-Server just lets authorized outsiders into your network but you have to make sure your Windows file archive PC is configured to share exactly what you want to with the desired remote user who will be logging on to your PC.
If you do it right they can see your shared drive in their File Explorer and you can even give them as much as full access to only that drive or certain folders if you want.
You can even go further giving them a full Remote Desktop but that's not necessary for them to just access a shared drive or folder.
In the newer Windows 10s you may now need to enable SMBv1 in Windows Features before you can share a Windows folder with an XP or non-Windows client. Previously enabled by default but now regarded as less secure than earlier updates.
Then you get laptops that want to log in remotely from random locations, that's when Windows itself on the laptop needs to handle its end of the VPN; when it's calling home to the office's VPN-Router, but when you don't have a matching VPN-Router at the laptop's end. Dynamic DNS is also real helpful on the laptops, so the home VPN will recognize the laptop from every location it tries to log in from, and for offices too if they don't have a staic IP.
This could be an even more confusing OS configuration effort with the laptop depending on Windows version, but after that the laptop can communicate directly over the VPN to the home endpoint, using the laptop's own Windows built-in VPN endpoint (after being enabled & configured to match the home office VPN-Router) therefore not needing a matching VPN-Router at the laptop's remote location.
But if you only have one Windows PC on each end and you want to link them by VPN, you don't actually need the VPN-Routers if each user just has access to do the port forwarding settings on your personal non-VPN routers. You can share the keys and current web IP or DNS addresses over the phone with the remote user for manual entry into each Windows configuration. Enabling each of the Windows' built-in VPN endpoints to do the handshake (without a VPN-Router at either end) and communicate more directly with each other over the encrypted web tunnel. Without needing to store the keys or pass unencrypted trafic within any routers either.
In Windows 10 you get going something like this:
https://helpdeskgeek.com/windows-10/how-to-set-up-the-window...
Looks a lot easier now.
Note that it still addresses dial-up which works about the same way when the laptop and Windows home server each had land lines available and telephone modems for alternate access to the same LAN. Dial-Up Networking from a laptop by phone modem could be accomplished by directly calling the office PC's private phone number (if not busy handling faxes or being on dial-up internet or something). Or if long-distance phone charges could apply, logging onto a local dial-up service like AOL to get on the web instead so you could get access that way when your office was online itself.
Once hooked up it's a breeze to use, even was on dial-up.
Actually FAT32 volumes had one less obstacle in the form of permissions.
