We'll need to check if this problem also occurs with NFS-Ganesha. Only very few development time is available for Gluster/NFS.
Steps to reproduce:
1. configure NFS-Ganesha without Kerberos enabled (NFSv3 enabled only?)
2. mount the NFS-export from Windows
While doing the mount, capture a network trace on the NFS-server and verify if Windows tries to mount with Kerberos first, and then falls back to AUTH_UNIX.