There is no "nfs4" filesystem type. If you want to use NFSV4, then
add "nfsvers=4" in the mount options field:

sudo mount -t nfs -o nfsvers=4 albus:/._disc1/sysadm/test1 /mnt/test1

You should also note that many NFSV4 hosts no longer support UDP (the
default NFS network protocol) and only work with TCP. You may need to
set the options to:

-o nfsvers=4,proto=tcp

for it to work under NFSV4.

 

 

 

Notes on NFS4 specficialy #mount -t nfs -o nfsvers=4