> Source: [sk167636](https://support.checkpoint.com/results/sk/sk167636)

# sk167636 - L2TP connection to the Security Gateway fails with the error "failed to write L2TP session params to kernel"

| Property | Value |
|----------|-------|
| Solution ID | sk167636 |
| Date Created | 2020-06-25 |
| Last Modified | 2025-07-08 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R81 (EOS) |
| OS | Gaia |

## Symptoms

- * L2TP connection to the Security Gateway / Cluster fails.

* The `$FWDIR/log/vpnd.elg` on the Security Gateway / Cluster Member contains these messages:

  `
  [vpnd PID TID]@HostName[Date Time][vpnd] L2TP_packet_arrived: Control packet detected - sending to L2TP handler`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] L2TP_control_packet_arrived: entering`  
  `
  [vpnd PID TID]@HostName[Date Time][SLP] L2TP_control_packet_arrived tunnelID: 00000000 00000000 00000000 00000000`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] handle_SCCRQ: Entering...`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] handle_SCCRQ: Searching for MSPI in XXX instances`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] handle_SCCRQ: L2TP control connection found in instance XXX, protected with MSPI XXX`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] loadL2TPTunnel: Could not find tunnel <XXX XXX XXX> in instances zero or 1`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] find_available_tunnel_ID: Trying tunnel ID XXX for peer XXX with port 1701.`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] loadL2TPTunnel: Could not find tunnel <XXX XXX XXX> in instances zero or 1`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] handle_SCCRQ: Storing L2TP_cluster entry in all instances`  
  `
  [vpnd PID TID]@HostName[Date Time][vpnd] saveL2TPCluster: error - failed to write L2TP session params to kernel
  `

## Cause

The kernel table "`L2TP_cluster`" is full in at least one CoreXL Firewall instance.

## Solution

This solution requires authentication. Please log in to view the full solution.

---

# Agent Instructions

This content is from the Check Point Support Center (https://support.checkpoint.com), the official knowledge base for Check Point cybersecurity products.

## Navigating This Knowledge Base

- **Complete index**: [llms.txt](https://support.checkpoint.com/llms.txt)
- **All SK articles**: [SecureKnowledge Sitemap](https://support.checkpoint.com/sitemaps/secureknowledge-sitemap-index.xml)
- **SK article URL pattern**: `https://support.checkpoint.com/results/sk/{skId}`
- **Markdown responses**: AI bot User-Agents automatically receive `text/markdown` content