mount – How to export an NFS mounted drive to nfsd in Linux (i.e. NFS proxy server)?

Suppose there is a server that runs NFS server version 4.0 or above, and I need to access some files on the server from a computer that runs NFS client version 3.0 or below. So what I want to do is to setup a proxy server at

Suppose the file I need to access is at, and in I do:

mount /path3/path1/

So now I can access the file through


mount /path2/path3/

After that, the path appears to be empty. Why is it happening? How can I fix it?