My NFS client says:
Version 2 unsupported by server

I have tried adding to /etc/sysconfig/nfs
mountd_nfs_v2="yes"
and
RPCMOUNTDOPTS="-V 2"

And I still get the error. How do I determine on the server side if NFSD has taken these options? We are running Centos 7.

Version 2 is on client with an old RamDisk that cannot be changed.

nfsstat -c
Client rpc stats:
calls retrans authrefrsh
90 0 90

Client nfs v3:
null getattr setattr lookup access readlink
0 0% 8 10% 2 2% 38 50% 19 25% 0 0%
read write create mkdir symlink mknod
3 3% 1 1% 1 1% 0 0% 0 0% 0 0%
remove rmdir rename link readdir readdirplus
0 0% 0 0% 1 1% 0 0% 0 0% 0 0%
fsstat fsinfo pathconf commit
0 0% 2 2% 1 1% 0 0%

Client nfs v4:
null read write commit open open_conf
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
open_noat open_dgrd close setattr fsinfo renew
0 0% 0 0% 0 0% 0 0% 2 16% 0 0%
setclntid confirm lock lockt locku access
1 8% 1 8% 0 0% 0 0% 0 0% 1 8%
getattr lookup lookup_root remove rename link
1 8% 1 8% 1 8% 0 0% 0 0% 0 0%
symlink create pathconf statfs readlink readdir
0 0% 0 0% 1 8% 0 0% 0 0% 0 0%
server_caps delegreturn getacl setacl fs_locations rel_lkowner
3 25% 0 0% 0 0% 0 0% 0 0% 0 0%
secinfo exchange_id create_ses destroy_ses sequence get_lease_t
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
reclaim_comp layoutget getdevinfo layoutcommit layoutreturn getdevlist
0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
(null)
0 0%

Check with if nfs v2 is advertised.

I added the following to /etc/sysconfig/nfs:
RPCNFSDARGS="-V 2"

I tried to restart nfs and nfs-config, but it was not until I rebooted that the change took affect. So I am not sure what other service needed to restart.