Setting up your own server to hack is great practice, especially because you can approach it from both an attacker and a defender standpoint. Once you learn how to exploit a particular vulnerability, you can then spend time learning how to secure your server against that vulnerability. Two sides of the same coin. You might check out r/homelab. Some of what those guys do is more complicated than you need, but a lot of people there run servers for hacking practice, and their setups range anywhere from a single Raspberry Pi or virtual machine to full racks of enterprise servers.