Based on this article Best Free Syslog Servers for Windows of 2020, I selected PRTG for its syslog receiver.
PRTG did a lot more, and I also let it run a few dozen sensors to ping various systems.
When the 30 day trial expired, my syslog receiver disappeared. I was able to re-install it, but I've lost 30 days of data. Can I restore that data?