I was finally able to work with QuickBooks support as you suggested.  We made a couple of changes to permissions on the QB folder, giving the QBDataServiceUser30 explicitly full permissions.  We also made changes to the service QBData30, changing the startup type from manual to automatic, changed the logon from the specific account QBDatatServiceUser30 to local system account, and checked the box to Allow service to interact with desktop.

2 days later, users are not able to go into multiuser mode.

Last night set an exclusion of the QB port number to prevent DNS from acquiring that port number.  We will see if that works.