// 2.2.2.7,Ubuntu 20.04.2 LTS
cat /etc/exports
/zion *(ro,fsid=0,sync,crossmnt,no_subtree_check,all_squash,hide)
/zion/share *(rw,fsid=1,sync,subtree_check,all_squash,insecure)
// 2.2.2.6,Ubuntu 20.04.2 LTS
cat /etc/fstab
2.2.2.7:/zion/share /zion nfs rsize=32768,wsize=32768,timeo=900,intr
// macOS Big Sur
sudo mount -t nfs4 -w -o sync,nosuid,nolocks,noatime,resvport,vers=4,nfsvers=4,soft,intr,rsize=32768,wsize=32768,timeo=900,retrans=3,proto=tcp -v 2.2.2.7:/zion/share /private/nfs
For NFSv4, there is a distinguished filesystem which is the root of all exported filesystem. This is specified with fsid=root or fsid=0 both of which mean exactly the same thing.
https://linux.die.net/man/5/exportshttps://linuxconfig.org/how-to-set-up-a-nfs-server-on-debian-10-busterhttps://forums.macrumors.com/threads/since-upgrading-to-big-sur-i-can-not-longer-mount-remote-nfs-drives.2274862/