Review the following information for IPv6 use:
For IPv6 functionality for NFS, you must use NFS version 4 in order to make the mount reachable. Note that NFSv4 requires several configuration steps in the operating system and NFS-related resources in VCS to enable it on the client and the exporting server.
AIX defaults to NFSv3, which does not work across IPv6.
Note that AIX's mount command refuses to accept IP addresses unless they are resolvable to a hostname.