Also tried all kinds of other stuff: slackpkg, USB-stick, ssh, but I can't get it done...
No internet connection (ran netconfig again).

So I found out the hard way.
After several hours of not getting e2fsprogs installed I gave up and reinstalled SW 12.2...
Everything is installed and configured the way I like it, so -in a way- the problem is solved. /home/ is on a separate partition (had some issues after reinstalling about getting it mounted, but worked that out) so it's not such a big deal.
It felt like a defeat, I borked my Slack box a couple of times before, but always found a way to get it working again (with help from others).

Anyway, what I'm am curious about is *why* is e2fsprogs needed when you don't use ext* filesystems?