Dell PowerEdge 840
I got this in 2012. It was old then. It's now 10 years old, but I'm still putting it to good uses. I run Windows Server 2012 R2 and use that as a file and Hyper-V server. Hyper-V is running two virtual machines: (1) A VPN server (CentOS with OpenVPN) and (2) An installation of Windows 7 which I use as an iTunes server to feed the Apple TV.