Partition Table: msdos
I'd say that GPT is a better suited partition table.
Create a bootable USB stick with the GParted ISO, and install the GPT partition table on the 8TB drive (all info will be wiped).
Then create the EXT4 primary partition, and after that, you could do a full disk check since it seems to be a new drive. It can take some time, but better be safe than sorry. Also check the drive's S.M.A.R.T. error log.
When that's all done, you're good to go with the RPi4 & LibreELEC.
SMBv1 has been deprecated (finally) by Microsoft, because the Swiss-cheese sized security holes in the file protocol.
SMBv2 is stricter, requires user credentials that must include a password, and network browsing has been disabled.
Kodi still supports SMBv1, but you'll need to change the settings in the Settings / System / Services / SMB Client / Minimal Protocol version.
When adding new sources, use the "Add network location.." option and enter all necessary credentials manually.
*I* watch TV on an 24" Monitor from exactly (measured) 1,5 m
Good for you, you (still) have 20/20 vision. 
Not everyone is that lucky anymore, age or diabetes can mess up your vision pretty good.
the sort order is as is /laid out !
Then Kodi/LibreELEC's sorting order is off, IMO.
Is this compatible with LibreElec?
LibreELEC is not in the habit of infinitely supporting older/prehistoric hardware.
If Ubuntu+Kodi works for you, then simply stick to it. Ubuntu has a larger video driver pool to choose from than LibreELEC.
The AMD E-350 APU has had good results in certain older LE releases, but based on the number of users of such ancient graphic cards, it's simply not worth the time and effort to keep up support for such hardware.
Most of your video formats should work on a AMD E-350, but a HEVC/h265 video will definitely stutter on your Foxconn box.
I never tried this option but perhaps it'll work for you, via the advancedsettings.xml : https://kodi.wiki/view/Wake_on_lan
not on an 24" screen from a distance of ~2 m (I guess not only for elder people with(!)/without glasses) !
This is not a typical distance/screensize combination. Have you ever seen someone being 2 meter away from a 24" screen in an office or home situation?
and decide which one is the oldest
Without looking: the top one, when the files are properly sorted.
I wouldn't mind adding machine info to the backup filename, especially with multiple LE devices flying around.
rpi4b-le-9.2.8-20211024002341.tar
rpi4b-le-10.0.0-20211024002341.tar
Thanks for any ideas.
Leave a proper debug log before you start messing around with other versions.
We have no crystal ball to see what is/was active on your LibreELEC setup, or what hardware you even use for LibreELEC.
Also please don't splatter your topic into someone else's forum thread.
Just create your own thread when it is not exactly similar to another one.
Are you also using a remote MySQL/MariaDB database connection? Other than that, try disabling Wireguard temporarily.
I've split your question into a new thread since it is a bit different from the thread it was placed into initially.
First of all, a NAS is designed to run 24/7. Having it go into suspend after 30 minutes idle already is quite quick. For example, I've set the my parents' NAS to only full shutdown at midnight. The drives though do not goto sleep once the NAS is active in the afternoon. There is also the question whether "constant" spin-downs and spin-ups are doing harddrives a favor. I have my "NAS" (a pc with a bunch of drives) on 24/7, my choice, and it all works fine (knock on wood).
The fact that it takes the NAS 10-15 seconds to respond is not Kodi's fault. I prefer myself to have some error msg in a few seconds over an eternally spinning http://wheel.Kodi/LibreELEC has a WOL feature somewhere, but I'm guessing it only works at Kodi's own boot moment (I never used it). Kodi cannot tell in advance whether HDDs in a NAS start to snore. So you may want to revise your 30-minute setting if you tend to watch something on multiple moments per day.
on the one hand the image is choppy, it seems as playing speeds are slightly variable
That is always the case with DVDs and CDROM discs. The rotational speed is different when the reading heads are at the outer tracks versus when they are at the inner tracks. The overall DVD throughput should be enough for USB2.0 connection. Choppy images can also come from damaged discs (error correcting that is active).
The question is also a bit: how "big" are the choppy moments, and how often do they happen? Every second, minute?
The other issue is that the audio track is not in sync, I need to compensate the audio in the audio settings.
That's what the audio settings are for... If you only or mostly do DVD discs, you can make default audio/video offset changes in the advancedsettings.xml file.
Filezilla should be fine too. Assuming the SSD will be used for storage only, the usual root folders should be created on it, so that Kodi can properly identify the individual sources types: movies, tvshows, tvrecordings, music and whatever is applicable. After that, the RPi4's Kodi sources can be pointed to those news locations, and normal operations can continue.
I don't know which flags are currently active on the drive, but formatting the SSD should at least overwrite some of them, if not all. I know that a readonly partition can stop the formatting of a drive though. Personally I use Gparted, but in a remote ssh session your options are limited. Just use whatever works and/or is available. The disk label of a EXT4 partition can also be set in the process.
but then would have to send send all of those multimedia content over the 50 kms over a 50 Mbit/s line (omg).
50Mbit isn't that bad if that's the upload speed. Using rsync or zsync would be an option, you could simply start the transfers in the evening and have them ready in the morning.
There are also Windows tools for doing EXT4 out there. On the other hand, running a Linux Live ISO such as Ubuntu can also be done from a bootable USB stick. With SMB support out of the box in Linux' File Manager, copying files is a breeze. And Kodi also has its own File Manager which supports "all" network protocols.
The SSD is connected to raspberry pi 4 externally via USB.
What counts, the OS running on that connected machine is Linux. Thus, EXT4 would still be my 1st choice.
Then again, Ubuntu Linux has been my daily driver system for the last 11 years, so I'm a bit biassed... 
A WiFi USB Adapter should be plug and play: it simply works or it doesn't work.
Team LibreELEC has no WiFi USB Adapter AC1300 to verify if it works "out of the box".
Before I do it, I wanted to get you opinion or experience
If you are going to use a SSD internally in a PC(?) and use LibreELEC, it's better (IMO) to format it to Linux' default EXT4 format. You'll have 100% compatibility and none of the NTFS shenanigans.
You could install Linux Mint again, via a bootable USB stick Live session, and do a dmesg listing in a terminal to see which hardware is present.
Paste the listing on a pastebin site so we can have a look.
Rufus should do okay with LibreELEC images. Otherwise try a previous release. It that works, updating LibreELEC is the next step.
