How is your AdGuard quest going? I am comfortable with *BSD systems as an amateur now. I have been enjoying my Opnsense and its implementation of Unbound DNS - it is rather clean, granular enough and stable. The hardware is about as old as yours: HP Z220. I threw in an old laptop 120GB HDD, there is no need to reboot this box for a long time anyway. It came with 16GB of ECC RAM, and the hardware utilisation levels are similar to yours. Works like a well-oiled machine.
