A firewall rule for TCP port 2049 is often enough to let an NFSv4 client reach a server. With NFSv3, it may not be: clients can also need rpcbind and other RPC services, some of which use ports assigned by the server. The useful first question isn’t just “What port does NFS use?” It’s “Which NFS version and services are this client and server using?” Start with the NFS version Port 2049 is the standard NFS service port. For the common NFSv4-over-TCP setup, it’s usually the mai...