Files On Server Not Accessible by Other Users

We are using Apple Server with a mix of Windows and Mac workstations. All of a sudden, I think after the latest Server update, files written by the individual workstations are no longer readable by the other workstations. This is happening on the Macs and Windows machines. We can go into the server and change the permissions, but it seems that the default is now to only let the creator of the file have access. Is there a way to change this default?