Netdata is exactly what you're looking for. It's basically an all in one monitoring and and alerting suite that collects and analyzes data, and provides a gorgeous web dashboard for you to view.
You can also manually replicate this using Prometheus, Grafana and other tools, but that requires a much bigger effort to set up.
The five node limit is a dealbreaker for me too. I'm also annoyed the free version doesn't have any real built in options to secure data by default. I followed a TechnoTim tutorial to get the NetData/Prometheus/Grafana stuff setup but it was too limited and required too much manual effort.