When main drawings are on local machine and references are on server, you need to resolve references using the Server Path Mapping Dialog Box.
To resolve external references:
The References dialog opens.
The Server Path Mapping dialog opens.
The missing reference now appears in the drawing and the path appears in the Saved Path field of the Reference Manager dialog box.
In the main drawing, set the Projectname sysvar to Project1. This value is saved in the drawing file.