Help: error 7 (RPC: Authentication error) when trying to mount FreeBSD 12.1-RELEASE NFS export on OpenIndiana Hipster GUI client

I have a FreeBSD 12.1-RELEASE machine, hostname DellOptiPlex390. I would like to export the folders /usr/home/jdrch/KeePass & /usr/home/jdrch/Sync and mount them via NFS on an OpenIndiana Hipster GUI machine with IP address 192.168.0.71. My username, jdrch, is the same on both machines. I therefore have the following: My /etc/rc.conf: hostname="DellOptiPlex390" zfs_enable="YES" kld_list="sysctlinfo" ifconfig_re0="DHCP" linux_enable="YES" dbus_enable="YES" dsbdriverd_enable="YES" sddm_enable="YES" sshd_enable="YES" nfs_client_enable="YES" webmin_enable="YES" smartd_enable="YES" ntpd_enable=YES ntpd_sync_on_start=YES rpcbind_enable="YES" nfs_server_enable="YES" nfsv4_server_enable="YES" mountd_flags="-r" mountd_enable="YES" rpc_lockd_enable="YES" rpc_statd_enable="YES" My /etc/exports: # Export /usr/home as read-write to OpenIndiana /usr/home -alldirs -rw -mapall=MyFreeBSDUsername 192.168.0.71 I'm exporting /usr/home because it's a ZFS filesystem and the [exports(5) manpage](https://www.freebsd.org/cgi/man.cgi?query=exports&sektion=5&manpath=freebsd-release-ports) seems to imply that's necessary. FTA: > All ZFS file systems in the subtree below the NFSv4 tree root must be exported After any update to either of those files I restart both nfsd & mountd on the FreeBSD server. Unfortunately, I haven't had any luck getting the export to mount. Trying to mount one of the export's subfolders fails: # mount DellOptiPlex390:/usr/home/jdrch/KeePass /export/home/jdrch/KeePass NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) nfs mount: mount: /export/home/jdrch/KeePass: Permission denied Trying to mount the exported filesystem also fails: # mount DellOptiPlex390:/usr/home/ /export/home/jdrch/KeePass NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) nfs mount: mount: /export/home/jdrch/KeePass: Permission denied Using sec=sys in the mount command doesn't work, either: # mount -F nfs -o vers=4,sec=sys DellOptiPlex390:/usr/home/jdrch/KeePass /export/home/jdrch/KeePass NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) NFS compound failed for server DellOptiPlex390: error 7 (RPC: Authentication error) nfs mount: mount: /export/home/jdrch/KeePass: Permission denied Substituting the FreeBSD server's IP address for its hostname has no effect. What am I doing wrong?