Update Server 2016

I have a Server 2016 (Hyper-V) that no longer allows updates. After loading the updates, they are also installed, but after the restart they are gone. No error is displayed. Everything with SFC and Dism was tested and did not work either. An error message said that the update path was wrong, but after deleting it, the SoftwareDistribution folder is filled again. We also tried to do an inplace upgrade from 2016 to 2016 (new installation). This also fails... does anyone have any ideas?

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