Unable to connect to NFS server across subnets on ESXi host
Article ID: 453196
Updated On:
Products
Issue/Introduction
NFS traffic on TCP/UDP ports 111 and 2049 fails between the VMware vSphere ESXi host and the remote NFS server when they reside on different subnets. This failure prevents the NFSv3 datastore from successfully mounting during standard operations or backup and restore workflows.
The following exact error message is observed in the logs: [esx.problem.vmfs.nfs.mount.failed] #.#.#.# /sd/mount/vmware/vmware-nfs-share Unable to connect to NFS server.
Environment
VMware vSphere ESXi 8.x
Cause
The ESXi host lacks a static route to properly direct outbound VMkernel traffic to the remote NFS server's subnet across a Layer 3 boundary. Without a dedicated routing entry to traverse the gateway, communication fails and SYN packets are dropped.
Resolution
Apply a static route on the ESXi host to direct traffic for the NFS server subnet through the appropriate local gateway.
- Access the affected ESXi host via SSH or the ESXi Shell.
- Execute the following command structure, replacing the # values with the specific environmental IP addresses and CIDR notation mask: esxcli network ip route ipv4 add --gateway #.#.#.# --network #.#.#.#/##
- Verify connectivity to the NFS server once the static route is applied.
Alternative Workaround:
Bind the appropriate VMkernel network adapter (e.g., vmk2) directly to the target NFS datastore to establish the correct communication path.
Additional Information
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