One day before Valentine's Day we take stock of our server adventures of the last weeks. The reason for encrypting anything was the "behavior" of our home server. It occasionally gave a bizarre error message, namely the message that the hard disk was full. Actually, that is not possible, because the only thing on the hard disk (or rather: SSD) of the home server is the OS, namely Ubuntu Server 19.10, as I reported earlier on November 5th. The space that the OS takes is at most about 10 GB. Of course, there is also the addition of slowly growing log files, but that cannot grow to 100 GB overnight!
Research showed that it was indeed caused by log files and in particular by error messages when calling the website on the home server. (http://erbenet.synology.me). That is a kind of dummy site that has not been done at all, but it is certainly there. The error messages were not only very many but also extremely cryptic.
Then what can it be?
Then it occurred to me that the panel app I'm using, Virtualmin, is not guaranteed for Ubuntu versions above 18.04. So I put the server back to Ubuntu 18.04, and installed all additional modules, such as Virtualmin, PHP, and Drupal, and tried everything again.... And then: damnotion! He kept making the same mistakes!! Digging even deeper into the error messages... Hey, it says something about "reading past eof" somewhere... so there's a file somewhere longer than it looks, or shorter than it looks. I ended up with the autoload file created by Composer in Drupal 8. It turned out that a lot of junk had been added beyond the expected PHP program code. Once that was corrected everything worked exactly as expected. Apparently the system had a hiccup at some point and corrupted the file size of this file. Can happen...
So it had nothing to do with the OS. So downgrading to 18.04 would not have been necessary afterward. Then upgrade again. To skip a few steps I passed the -d option to "do-release-upgrade". To my amazement, my system was upgraded from 18.04 to 20.04 all at once. The latter is brand new, not even officially published yet, and fully in the development phase, but the -d option made me open to it. Actually nice to work with something so new, only... it doesn't work. At least not on the server. And what exactly didn't work was the network connection and that is quite important for a server. Googling it turned up the knowledge that it is probably a driver problem. Such a new variant of an OS has not yet been expanded with drivers for all kinds of network cards. My motherboard has a bit of an oddball ethernet chipset, which works fine under previous versions of Ubuntu, but not (yet) under 20.04. So back to 18.04 and everything under it activated again and got it to work and then upgraded to 19.10.
So we are back to the point where I started on November 5th. enriched with a lot of useful experiences...

In addition to Windows 10 and a version of Puppy Linux, I also installed a version of (K)ubuntu on my laptop. In the meantime, it had also grown to 19.04. Out of curiosity, I also upgraded it to 20.04. And that works! The WiFi chipset of the laptop is very usable for Ubuntu 20.04. So my laptop runs the latest of the latest from multiple OSes! And this freak likes it...