> Source: [sk183638](https://support.checkpoint.com/results/sk/sk183638)

# sk183638 - Site-to-Site VPN tunnel using ikev2 fails to establish when the Security Gateway has multiple external interfaces

| Property | Value |
|----------|-------|
| Solution ID | sk183638 |
| Date Created | 2025-07-21 |
| Last Modified | 2025-08-27 |
| Technical Level | General |
| Products | Security Gateway |
| Versions | R82, R81.20 |
| OS | Gaia |

## Symptoms

- * Check Point Security Gateway fails to establish VPN tunnel using ikev2.

* Running IKE debug (per [sk180488](https://support.checkpoint.com/results/sk/sk180488)), the *$FWDIR/log/iked.elg* file show similar logs:

  ```
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] Message::addPayload: Too many payloads
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] natTraversalHandler::createNatTNotifyPayload: Failed setting Notify payload on message.
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] Exchange::startPrepareMessage: error encountered. has notifications to send: 0
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] Message::~Message: entering
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] Exchange::setStatus: Changing status from: initial to: failure (final)..
  
  [iked2 6774 4066816448]@xxxx[x Jun xx:xx:xx][ikev2] Exchange::setLog: Setting log message:
  Configuration problem.
  ```

  <br />

## Cause

This issue occurs because the Security Gateway sends a NAT Discovery (NAT-D) notify payload for each external interface.  
To comply with Internet Key Exchange version 2 (IKEv2) standards, the size of the negotiation packet must remain within defined limits.  
Check Point Gateways currently enforce a maximum of 25 NAT-D payloads per packet. If the number exceeds this limit, the tunnel establishment fails.

## Solution

[Contact Check Point Support](https://www.checkpoint.com/support-services/contact-support/) to get a Hotfix for this issue.  

A Support Engineer will make sure the Hotfix is compatible with your environment before providing it.  
For faster resolution and verification, collect these files:

1. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Management Server involved in the case.
2. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Security Gateway / each Cluster Member involved in the case.

Hotfix installation instructions:  
Refer to [sk168597 - How to install a Hotfix.](https://support.checkpoint.com/results/sk/sk168597)

---

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