Here is how to quickly show the connected clients to a NFS server. It might be useful to know before rebooting the server!
On the server, execute the following command (replace <> with the NFS server IP address) :
netstat -an | grep <NFS.Server.IP>:2049
netstat -an | grep 192.168.45.32:2049
You should see a similar output :
tcp 0 0 192.168.45.32:2049 192.168.45.52:840 ESTABLISHED
tcp 0 0 192.168.45.32:2049 192.168.45.22:980 ESTABLISHED
tcp 0 0 192.168.45.32:2049 192.168.45.42:859 ESTABLISHED