Hey oisin53,
If your NAS is using SMBv1, you'll have to enable SMBv1 on the W10 PC's and you probably only need the SMBv1 Client, but don't quote me on that. If you do have to use/enable SMBv1, you should uncheck the Automatic Removal.

Enable or Disable SMB1 File Sharing Protocol in Windows | Windows 10 Tutorials

Note: Some NAS you can change the SMB version, so I would look into that first.