I wanted to let you know that the article listed below needs some updates based on new networking requirements I have observed in my firewall logs.
The listed ports should include port 80/TCP and port 123/UDP.
Port 80/TCP for http health checks.
Port 123/UDP for NTP checks that the Sense device makes to public time servers. (time stamps being exceedingly important for the sense data platform.
For some more advanced troubleshooting, if the sense monitor appears offline, check that the ISP is not blocking public DNS servers as Sense now uses hard-coded DNS servers: 18.104.22.168, 22.214.171.124, and 126.96.36.199.
Hope this helps.