diff --git a/content/kb/troubleshooting-rwx-volume-fails-to-attached-caused-by-protocol-not-supported.md b/content/kb/troubleshooting-rwx-volume-fails-to-attached-caused-by-protocol-not-supported.md
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+---
+title: "Troubleshooting: RWX Volume Fails to Be Attached Caused by `Protocol not supported`"
+author: Derek Su
+draft: false
+date: 2023-10-27
+catelogies:
+  - "volume"
+---
+
+## Applicable versions
+
+All Longhorn versions.
+
+## Symptoms
+
+Attempts to attach an RWX volume are unsuccessful, and the workload using the volume is unable to start. The logs contain the following messages:
+```
+Oct 11 07:42:23 dev-worker-1 k3s[1294]: Mounting command: /usr/local/sbin/nsmounter
+Oct 11 07:42:23 dev-worker-1 k3s[1294]: Mounting arguments: mount -t nfs -o vers=4.1,noresvport,intr,hard 10.43.207.185:/pvc-13538170-4278-4467-b2b0-1f1ba6f54a4c /var/lib/kubelet/plugins/kubernetes.io/csi/driver.longhorn.io/185c34f566c2eca6e8c7c6a2ede2094c076d7d25ddae286dc633eeef80551af0/globalmount
+Oct 11 07:42:23 dev-worker-1-autoscaled-small-19baf778f50efd8c k3s[1294]: Output: mount.nfs: Protocol not supported for 10.43.207.185:/pvc-13538170-4278-4467-b2b0-1f1ba6f54a4c on /var/lib/kubelet/plugins/kubernetes.io/csi/driver.longhorn.io/185c34f566c2eca6e8c7c6a2ede2094c076d7d25ddae286dc633eeef80551af0/globalmount
+```
+
+The issue applies to RWX volumes on hosts running OpenSUSE MicroOS (from 2023/10/08 to 2023/10/21) and other distributions using version 6.5.6 of the Linux kernel.
+
+## Reason
+
+The cause of this issue is a regression of the NFS protocol in Linux kernel 6.5.6. Because of the regression, NFS clients are unable to connect to an NFS server inside a share manager pod.
+
+#### Solution
+
+To address the issue, you can perform the following actions:
+1. Upgrade the operating system to a version using Linux kernel 6.5.7 or later.
+1. Downgrade the operating system to a version using Linux kernel 6.5.5 or earlier.
+
+## Related information
+
+https://github.com/longhorn/longhorn/issues/6857
+https://github.com/longhorn/longhorn/issues/6887