I have now removed the small update and done some testing with external ldap to the older system. This functions as expected but it is no solution for our company.
I have done an import of the settings.cnf file from the old storage for experimental testing.
I transfered only the CONFIGURATION, not the SETUP. This seems to be the only way to get the users and groups transfered to the newer system. After successfull reboot the list for shares, users and groups shows me the settings i want to see.
I exported the user and group IDs into a file but this was empty as expected because of the deinstalled small update. After applying the small update again, the export was successfull. The test export shows the same settings as in the old system.
I will now check the rest of the settings. If everything is OK i will copy data on the system for further testing.
btw. settings.cnf was exported from DSS 5.0up62 build 3518 to DSS 6.0up75 build 5377 !