4 X 4TB Seagate Ironwolf w/ SHR1, currently ~50% capacity
APC UPS
It's overbuilt for what it does. I'm using Veeam and iDrive clients to back up PCs to it, and iDrive to back the NAS up to the cloud. Playing with some Docker containers like Plex, Speedtest-tracker, Dokuwiki, Lidarr/Radarr/Sonarr/SABnzbd, VaultWarden. I've briefly used it as DNS, DHCP, web, FTP server over the last few years. It's a nice home lab environment to relearn all the IT stuff I used to do at work, but on a much smaller scale.
The original drives are healthy at 28000 hours. End-of-life is at least a couple of years out (hopefully), but I'd probably look at something like a 423+ with 4-6GB RAM and 2-3 10TB drives as a replacement until the next shiny thing comes out. RAM isn't as critical with Docker, so my current 12GB config is overkill.
Thanks; looking forward to useful tips from the community.