This can appear as a Heartbeat Timed Out alarm and indicates a network problem between the appliance and the Control Center. Typically, the appliance is not able to reach the Control Center at all, resulting in this message only appearing on the appliance's CLI. The Control Center will only know that the appliance has not contacted it, but not why.
The two most common network problems are Routing and Firewalls.
Ensure that the appliance is pointed to the correct IP in config system management. There should be a valid route to this IP address from the appliance's network.
The appliance will attemp to connect to port 8443 on the target IP. Any firewall in between should allow this traffic.
If the appliance shows up as yellow in the Inventory, then it is operating in Minimal Heartbeat. This is most often caused by a version mismatch between the appliance and the Control Center. Heartbeat requires the same minor revision to operate in Full mode. For example, a version 4.2.0 Control Center can communicate with appliances running 4.2.0, 4.2.1, 4.2.x, etc.
While in Minimal Heartbeat, only basic information will be exchanged with the server. Upgrade/downgrade the appliance to the same minor version as the Control Center to resolve this issue.
Sometimes, a software bug can cause a problem with the Heartbeat function. This usually presents itself as Heartbeat Failed (Internal HTTP 500 Error). Depending on where Heartbeat is failing, this message may or may not make it to the Control Center.
Temporary Heartbeat alarms may occur when new appliances are added to the inventory or upgraded. If the Control Center is restarted or shut down, all appliances will generate alarms indicating that they cannot reach the Control Center. This is normal.
If a Heartbeat alarm persists for several minutes, please contact Uplogix Support for assistance.