To determine where the NFS service has failed, you need to follow several procedures to isolate the failure. Check for the following:
Can the client reach the server?
Can the client contact the NFS service on the server?
Are the NFS services running on the server?
During this process, you might notice that other portions of the network are not functioning. For example, the name service or the physical network hardware might not be functioning. For information about naming services, see Working With Oracle Solaris 11.4 Directory and Naming Services: DNS and NIS. Also, during the process you might see that the problem is not at the client end, for example, if you receive a problem from every subnet in your work area. In this situation, assume that the problem is the server or the network hardware near the server and start the debugging process at the server, not at the client.