We believe the agent is still running as we are getting occasional alerts. But DT is no longer showing any of our hosts and processes. Smartscape threw the above message for the host.
Deployment status can see the hosts if looked up - none in the last 72 hours, but under "All hosts" it says either "Host or monitoring unavailable" or "Host monitoring state is unknown".
Where to look and how to restore DT full monitoring ?
If you have the oneagent in place and running and you can confirm that, then you need to check the firewall rules. It sounds like the oneagent is running and the oneagent is getting out from time to time so it might not bee the firewall. So, if you have an antivirus software, make sure that the system excludes the oneagent and its operating directory. as I have seen it where an Antivirus platform will kill the oneagent process and cause issues in the UI.