We have a 2-node cluster with NW60SP5 of which one node abends with
message as seen in hp Proliant Integrated management Log Viewer:

Abnormal Program Termination (Abend: At least one of the nodes is Alive
in the old master's node partition. This node is NOT the old master's node
partition. For more information, consult te Running Process:
VLL_EventThread Cod)

Abend.log does not record any of these abend instances.
We recently migrated from a public to private network, however all
cluster nodes and resources have static private IPs.

I thought maybe increasing the heartbeat default=8. What would be the
recommended value and if this is increase what else should be increased
or decreased?

Please advise.
Thank you.