I do not recommend that you do this with either server or with peer to peer.
Best Practice is to use FileMaker Pro or FileMaker Server to host the database from the machine where the file is physically located. This file is then opened with FileMaker Pro or FileMaker Server on that machine and others use the Open Remote method to find and access the database file. Each user must have their own licensed copy of Filemaker to access the database at the same time. This requires purchasing separate copies of Filemaker or a volumne license key that permits multiple installs from the same key.
And please avoid putting the database file in a shared directory at all costs. If two users attempt to directly open the file at the same time, you can end up with a damaged database file. And if you open the file on a remote volume on your computer and then others use Open Remote to access the hosted database there is still some risk of damage to your file should a network "glitch" occur at just the wrong instant.
Thanks for the heads up.
You don't need to use FMS but can HOST up to 10 valid licenses [including the HOST]. That means HOST traffic is limited even if you have 20 valid licenses.