3 Node Cluster, Nodes Disconnect

[#1]

Hello, I have a 3 node NiFi Cluster (nifi1, nifi2, and nifi3), using v 1.19.1.  

The nodes are each disconnecting consistently from the cluster.  They connect, and then disconnect, and then reconnect, and then disconnect over and over...

On nifi1, when I log into the GUI, a warning on the right side of the GUI indicates:

Event reported for nifi3:9443- Node disconnected from cluster due to Have not received a hearbeat from node in 338 seconds.

In the nifi GUI, logging into https://nifi1:9443/nifi, under the cluster section, when i first open this display,  no nodes are indicated as connected.  When I open the cluster window, an error message "Cannot replicate request to Node nifi1:9443 because the node is not connected.  Then, if I wait several minutes and refresh the screen, then all nodes are showing as connected, and then after another refresh nodes disconnect.

There is similar behavior when I log into https://nifi2:9443/nifi. I see a repeating error that includes nifi1, nif2 and nifi3...i.e., Event Reported for nifi3:9443 - Node disconnected from cluster due to Have not received a heartbeat from node in 1230 seconds, and these warning messages repeat with nifi1 and nifi3...

When I attempt to log into nifi3, i am unable.  I receive the following error message:

Cannot replicate request to Node nifi1:9443 because the node is not connected.

Can you please advise why this behavior is occurring.

[#2 · Accepted solution]

I solved my own issue.  

I corrected configuration settings in each respective zoo.cfg associated with each zookeeper host. The parameter Server.1 was erroneously pointing to each zookeeper host.  Replaced this with the private IP address of each nifi node.