[UPDATE 2021.07.17] Up to now, the maximum time that the server managed to run continuously without a single restart in any of the running services has been 377 consecutive days. You ma find the suspected reasons for the SD corruption hereAlthough the server was still running, I detected a corruption in the SD. A full restore of the latest backup onto a new SD was required to have the system up and running again.
[UPDATE 2023.03.25] The SD corruption problem was identified to be caused by the files that were modified in the DHCP process. Although I had set a never-expiring IP address in my DHCP server for my Pi, the communication between the DHCP client of the Pi with the DHCP server, kept updating the local files, causing eventually the SD corruption. In spite of the fact that the management of the IP addresses of all computers in my local network would be much easier if performed centrally, it seems that a fully static IP address need to be set-up. Since the repair, the server is running for 244 continuous days without problems.