The way Firebird works is NOT using shared file access the way a file
server shares files. If that is what you are attempting then it simply
will not work.

Instead, the clients communicate across the LAN with the Firebird
program running on a single database server machine. The clients usually
do not directly see the database file itself and if they can see it on
the "file server" that is irrelevant.

The only way the clients can use Firebird to access local databases is f
they are each also acting as Firebird servers. In that case, they would
each have the full Firebird software installed on them, not just the
Firebird client.

So, I am still confused about what is actually going on here.

What is the name of the database file on the server and where is it
located (the full path)? And what is the name of one of the local
databases files?

Also, is this Delphi program one which you have the source code for?