Access a folder on another computer? Windows 10 to Linux

There are multiple ways of doing this.

In addtion to the likes of Dropbox, One Drive there are also solutions to allow you to roll-your-own equivalents - Owncloud and Nextcloud spring to mind.

Alternatively you may want to consider bridging your networks using a VPN and using something like SMB (windows file sharing - SAMBA on Linux) or NFS. (The VPN is not strictly speaking neccessary if you have atatic IP addresses, but it does a lot for security of your data)

There are two ways to do this:

• The folder is hosted on both computers and synchronized.

  Aside from the usual cloud services (dropbox etc), there are a few programs for synchronizing folders without using cloud storage, such as Syncthing or Resilio sync. The latter two work on both Windows and Linux (and macOS).

  Advantages: File access is equally fast on both machines, since the files are local. Most sync programs of this kind will automatically go through NATs and firewalls, making "not the same network" mostly irrelevant.

  Disadvantages: The folder occupies space on all machines involved. Changes take a few moments to show up. If several people edit the same file at the same time, you'll end up with a lot of "myfile (conflict).ext" copies.

• The folder is hosted on one computer, and accessed from another.

  When a Windows machine is involved, remote file access would typically be done using either SFTP (e.g. sshfs) or SMBv3 (samba). Maybe also WebDAV.

  The mentioned protocols are just typical TCP/IP services that could be accessed across NATs using "port forwarding". However, connecting the two machines to an internal VPN would be a better alternative (such as Tailscale or ZeroTier or Hamachi), both for security and for making the NAT/firewall traversal much easier.

  Advantages: If the folder is large, it only needs to be stored on one system, possibly saving disk space.

  Disadvantages: Needs a fast internet connection (on both systems, in both directions!) otherwise it'll feel really sluggish. Clients must have an account created for them on the server machine's OS. All the protocols need port-forwarding and stuff; SMBv3 pretty much needs a VPN, as it's still kind of a risk otherwise and many ISPs still block it direct. On the other hand, SFTP (sshfs) needs a third-party client on Windows, it's not as nicely integrated as SMBv3 is.