I am currently configuring Nagios Xl on our client proof of concept. I already successfully installed NagiosXl and agent on Linux-server(client-server) that will be monitor.
Now I'm starting to monitor the Linux-server and configure it, and I got this error. Actually, this is the second Linux-server that I am monitoring. The first one, it is successful. But on the 2nd Linux-server, when I look at the View, this is the result...

Can you please advise or guide me on what troubleshooting should I do for me to successfully monitored that Linux-server, and was able to see the status of being "ok"...
Thank you very much,
John Benedict Maliwat
Philippines