Many 1,2TB HGST 2,5" 10k RPM SAS drives For backup some WDs out of external cases

I have multiple things I tested and learned.

Firstly an opnSense firewall.

An Active Directory (aka setting up a Domain Controller with DNS etc) with a test client, DHCP failover (active passive)

When you have an AD (=Active Directory) you should try to set up an Exchange server, making mail flow rules etc. maybe a cluster

Docker

Reverse Proxy

And last but not least setting up Vlans -> I have a basic understanding and know how it works (and should be set up) but sadly haven't actually configured it here at home

And virtualizing things and get some hands-on experience with VMware/Hyper-V/Proxmox/QEMU etc.

That are the things I have learned and improved my skills with at home -> At work we have no opnSense firewalls, but for learning setting up pfSense, opnSense or using an old firewall (regardless of the manufacturer) helps understanding access rules, NAT PAT etc.