I’d say anyone wanting to go this deep into a home monitoring setup will likely go with what works best for them instead of reading and following the entirety of this guide… I’m one of those people…

Wrote my own log parsing software to put into a database, display and alert through grafana, which is alerting through a homemade webhook that sends a notification to ntfy based on severity… And I also use uptime Kuma like mentioned, but my notifications channel is ntfy. No cloudflare for my internal services, only wireguard to connect home and use everything. And definitely no telegram.

Plenty of other stuff setup, but my security alerts and monitoring rely heavily on the syslog/grafana server which helps me monitor everything.

If you have a pi or Linux box, try setting it up as a syslog server. Then tell opnsense to use that for forwarding logs to. Doesn’t guarantee you’ll see what went wrong, but maybe it’ll help.

I’m not sure opnsense has journalctl or something similar, but that would be a good place to look for some history, too.