[Techtalk] Looking simulators for learning

[Figaro]

Hello all.
I have been asked by a group of persons  (7-10 elder who are looking to
understand computer technology) to locate networking simulator software .
They would like to learn network and web server administration through
simulations. Most are using Debian or some flavor thereof such as
Knoppix (no Ubuntu) one has Slack.

Anyway. I'd promised to inquire and report back at the next Resident
Council Meeting (they live in an assisted living facility). I remember
there were once several specialized distros avail. for training and
certification prep. that had extensive admin. simulation and simulated
services, but have not seen them recently.
Any help gratefully appreciated.

As always,
Thank you,
matthew