> Source: [sk180253](https://support.checkpoint.com/results/sk/sk180253)

# sk180253 - "first packet isn't SYN" drops after a cluster failover 

| Property | Value |
|----------|-------|
| Solution ID | sk180253 |
| Date Created | 2022-11-16 |
| Last Modified | 2025-11-24 |
| Technical Level | General |
| Products | Security Gateway, Scalable Platforms |
| Versions | R81.20, R81.10 (EOS), R81 (EOS), R81.20, R81.10 (EOS), R81 (EOS) |
| OS | Gaia |

## Symptoms

- When a cluster fails over, connections are dropped because "`first packet isn't SYN`".

## Cause

The Delta Sync packet is rejected if the timeout of the connection is identical on the local and remote members.

In such a scenario, cluster members do not synchronize the connection.

As a result, after a fail-over, the new Active cluster member drops it as an "`out-of-state`" packet.

## Solution

This problem was fixed. The fix is included starting from:

* [Jumbo Hotfix Accumulator for R81.20](https://sc1.checkpoint.com/documents/Jumbo_HFA/R81.20/Default.htm) starting from Take 2
* [Jumbo Hotfix Accumulator for R81.10](https://sc1.checkpoint.com/documents/Jumbo_HFA/R81.10/Default.htm) starting from Take 110
* [Jumbo Hotfix Accumulator for R81](https://sc1.checkpoint.com/documents/Jumbo_HFA/R81/Default.htm) starting from Take 87
* [Jumbo Hotfix Accumulator for R80.40](https://sc1.checkpoint.com/documents/Jumbo_HFA/R80.40/Default.htm) starting from Take 198

If you choose not to upgrade, [contact Check Point Support](https://www.checkpoint.com/support-services/contact-support/) to get a Hotfix for your version.

A Support Engineer will make sure the Hotfix is compatible with your environment before providing it.  
For faster resolution and verification, collect [CPinfo](https://support.checkpoint.com/results/sk/sk92739) files from the Management Server and Security Gateways / Cluster Members 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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