Defining the network first would help in getting suggestions.
Wired or wireless?
Number of computers?
Router, switch or hub? Make and model?
The router may be failing or the configuration corrupt.
Have you tried restarting the router and noting the dropout frequency?
The database is on a server or a workstation?
Is the database shared with FM server or FM?
Are the dropouts more frequent at a time of day?
Is any monthly maintenance done on the computers?
What is the exact version of FileMaker and the Operating System?
If filesharing is turned on, when the dropout happens can you still see the machine doing the serving?
wireless, 2 relatively new imacs (sometimes a laptop as well) I use an airport express for the router and it is brand new. I've restarted it before with no changes. The database is just on one of the computers in the house (that I have the backup connected to) Using Filemaker Pro 9 on both computers. I do some maintenance regularly. My husband is using filesharing to access the database and he will lose the connection quite randomly and the error message comes up that the network connection is lost. He shuts down filemaker and then when he tries to start up filemaker again it tells him that the computer is already connected to the database that only one user can access from that computer... (or something like that) He then has logged out as a user on the computer itself or does a restart. Then it lets him connect. Its just annoying to be working on something and lose the connection and typically lose the file....