This issue will occur if the IP address changes or if a firewall is enabled.
Release : 8.5
Component : UIM - ROBOT
Please note that CentOS 5 is end of life by Cent OS. See https://endoflife.software/operating-systems/linux/centos
Broadcom follows the best practice of following the manufacturer's end of support for OS. CentOS 5 is not supported past UIM 8.51 and is currently best effort.
Broadcom recommends for security either upgrading the OS or retiring the server.
If the IP changed, you can use Infrastructure Manager to validate security which should correct the issue. Right click on the probe, select security -> validate.
If your firewall is enabled, please follow the published directions for the specific OS to disable.