What should I do with my Active Directory Lab?
Create an Active Directory domain in a virtualized environment (Hyper V or VMWare). Once you setup a basic AD server, connect some machines, enable/delete/edit users and groups, and grant permissions through AD groups and roll out software and setting through GPOs, you’re already more competent than most helpdesk people. Incorporate Linux based servers and applications into your setup. As there will be almost no load, you can add VMs with almost no resources so with a decent CPU and 32Gb you can set up quite a few servers.
The above is excellent to combine with learning PowerShell and virtual machines. ProMax is great and well my favorite but VMWare ESXI and Hyper-V is more traditionally used in enterprises so they’ll make for better simulations.
And when you’ve set all that up, learn backups with software like Veeam. Then break some of your VM’s, and restore it from backups.
Look up the concept of high availability and try to implement that somehow.
Add application servers and workstations and use Group Policy to deploy and configure the machines.
However, setting up services on Docker in Linux is also a lot of fun, and is very relevant, if you’re going the Devops route.
This is definitely more “fun”, since you can set up web services that you run every day for stuff, and even share it friends. Like Nextcloud, VSCode, Plex, Jellyfin or some note-taking services or whatever floats your boat.
What you’ll learn there (reverse proxies, SSH, pub/private key authentication, basic networking, Linux, CLI etc) will also be very relevant in many enterprise settings.
What If I want to learn about networking?
To learn about networking, Cisco Packet Tracer is a good option and there’s loads of tutorials available.
GNS3 is also a network device emulator, and more than a few devices requires lots of CPU and RAM resources. The Caveat here is that you need to pay for a license for each device you want to emulate.
What about CyberSecurity?
If you want to progress on to some security/hacking then Tryhackme, Hackthebox, Portswigger all have free resources (and some cheap paid for resources to help you on your way.
But, just keep making things and then breaking things. Building an AD Domain with multiple servers and workstations and configuring all of the above can be done on a single machine in a few hours. So do it multiple times using multiple methods and try stuff. VMs allow you to take snapshots so you can mess about and then just roll back.