6027-2728 [N] Connection from node rejected because it does not support IPv6
Explanation
A connection request was received from a node that
does not support Internet Protocol Version 6 (IPv6), and at least
one node in the cluster is configured with an IPv6 address (not an
IPv4-mapped one) as its primary address. Since the connecting node
will not be able to communicate with the IPv6 node, it is not permitted
to join the cluster.
User response
Upgrade the connecting node to a version of GPFS™ that supports IPv6, or delete
all nodes with IPv6-only addresses from the cluster.