I did the restoration. Stand is now Joomla 3.7.5, PHP 5.6.30, jDownloads 3.2.56.
The general Joomla access rights for the groups are now functional again.
jDownloads "reacts" the same way now, it does not adjust the download area. With manual access the error with the access authorizations comes again or with automatic adjustment the representation is destroyed and although the adjustment on-line is indicated, but it does not run.
This is now very misterious because in the state previously until 08.12.17 data according to the protocol, which were added, have also been read.
With this stand from 17.11.17 this is no longer possible.
I do not have full rights to the Linux, but since I took the bug with it in the recovery state, I'm worried that this is something that the provider side has affected.