If this is only happening at the user level, it's not the network going out, but rather the user's network connection.
I dealt with intermittent network issues at the user level many years ago. Synching shouldn't wipe out other peoples work. When a synch fails, make sure the user saves their local file. It usually happens before the synch with central fails, so that shouldn't be a problem.
If this network issue is going to continue for any length of time, I would consider setting up a workflow that requires checking out worksets to avoid any conflicts with editing the same elements by different users.
Rob
Drafting is a breeze and Revit doesn't always work the way you think it should.