Sharing a data file over the internet via VPN is too slow and we have never seen it work properly and is not supported.
So you have a couple of options
1. You can install TATEMS to another computer that nobody uses at the same location where the computer housing the database is located. Then network that one together with database on the server using GB ethernet.
Then remote into that computer from the second location (home, etc.) using something like GoToMyPC or Team Viewer or Zoho Assist to run TATEMS remotely. (Zoho Assist has a free version with unattended access)
Here is how to setup standard networking
2. Install TATEMS on a Windows Remote Desktop Services Server and then have the remote computers remote into the server to run TATEMS
Here is instructions on how to setup TATEMS on a RDS server for multiple users
3. Use our cloud TATEMS cloud service which is the exact same software except it is running on our RDS server in the cloud that you can access from any internet connected computer for a monthly fee of $127 per month for the 1st user and $100 per month for each additional user. Each each user would share the same database. 2 people can not share the same login name at the same time.
You can try standard networking over your internet VPM network but I can pretty much guarantee it will be so slow on the remote computer that it will be unusable.
You own 3 TATEMS licenses.
With the first option above you can have TATEMS installed on up to 3 computers. This could be 2 workstations that people use at the office plus one that is used strictly for remote access, Any computers that remote in to the one waiting for remote access do not need a licenses because TATEMS is only running on the host machine that you will be remoting in to.
With the 2nd option above you need a license for each simultaneous user that will be remoting in to the server plus any workstations that still have TATEMS installed in a mixed environment.