I managed to configure NFS like this:
Privilege: Read only
Extra options: subtree_check,secure,root_squash,anonuid=1004,anongid=100
The client is Dune HD Base 3.0 media server. Wireshark log shows it has host name 'tango3' and GID 0 and UID 0.
Issue: when I change IP address to 'tango3' - client cannot access NFS server... I need name (not IP address) because IP address of client is not constant.