It seems so, that the Build 2922 stores the configuration in a other way than the Build 2956. I updated yesterday and after the update all my NAS configurations are gone. The rights on the filesystem are still there, so i created the same users and groups again. (In the order i created it the first time, so they got the same ID's.)

Some other configs where gone too, but no data where lost here...

After rolling back to the previous systems all configs are back again and when i update again the same settings i made after the first update are back too.