Timestamp are not correct

Hello, sorry for the late reply, but I have now found the problem. The server I am using was installed and configured by our hoster. An error was probably made with the tzdata program. No matter which time zone was set, everything was changed to cest +2 in the background. A reinstallation and reconfiguration using “apt-get --reinstall install tzdata” and a subsequent configuration using “dpkg-reconfigure tzdata” solved the problem for me. Many thanks for your help, this has put me on the right track. Another problem was the missing time zone on the server from which the backup was made. After this was also set, the data in the backup was also correct.
The ticket can be closed.