> Source: [sk179651](https://support.checkpoint.com/results/sk/sk179651)

# sk179651 - One way audio over Security Gateway fails after upgrade - Stability improvements for VoIP (SIP / H323) and other data conneciton

| Property | Value |
|----------|-------|
| Solution ID | sk179651 |
| Date Created | 2022-07-04 |
| Last Modified | 2025-09-03 |
| Technical Level | General |
| Products | Security Gateway, Spark Firewall (Locally Managed) |
| Versions | R82, R81.20, R81.10 (EOS), R81.10.X, R81 (EOS) |

## Symptoms

- * Complex Control / data connections are dropped at random at VPN tunnels after upgrade.

* Kernel debug (`fw ctl debug -m fw + drop`) on the Security Gateway shows these drops:  

  ```
  
  "dropped by vpn_encrypt_chain Reason: no error"dropped by vpn_encrypt_chain Reason: no encryption key for destination;
  vpn_outbound_policy_chain: this chain was already went through vpn_before_offload() -> SKIP ;
  dropped by vpn_decrypt_verify Reason: CONN_ENC_SERVER with client to server packet;
  vpn_encrypt_chain: MSPI is not available for the packet direction.
  ```

* Data connections (RDP / RTP / FTP/ ETC) are sent in "clear" instead of "encrypted".

* Running the (`fw ctl zdebug + nat | grep NATed`) command on the affected Security Gateway shows this log:  

  ```
  
  fwchain_get_nat_conn: dir a, 1.2.3.4:12058-> 9.8.7.6:12992 IPP 17 is NATed to dir b, 5.5.5.5:443 -> 6.6.6.6:62800 IPP 6.;
  ```

  Where the IPs or the Ports or the Protocol is changed to an UNKNOWN NAT.  
  \*In the example we see that all of these changed (it is an example)
* SIP traffic is dropped with "*dropped by cphwd_cpasglue_handle_packet Reason: CPAS: failed to init streamh;*"

## Cause

A code limitation in the NAT infrastructure causes complex connections to inherit NAT from a non-related previous connection.

This issue affects these products in conjunction with complex connections (for example VoIP):

* VPN
* Cluster
* NAT
* Routing
* Secure XL

<br />

## Solution

This problem was fixed. The fix is included in:

* [Jumbo Hotfix Accumulator for R82](https://sc1.checkpoint.com/documents/Jumbo_HFA/R82/Default.htm) starting from Take 41
* [Jumbo Hotfix Accumulator for R81.20](https://sc1.checkpoint.com/documents/Jumbo_HFA/R81.20/Default.htm) starting from Take 43
* [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 82
* [Jumbo Hotfix Accumulator for R80.40](https://sc1.checkpoint.com/documents/Jumbo_HFA/R80.40/Default.htm) starting from Take 198
* [Firmware R81.10.08 for Quantum Spark](https://support.checkpoint.com/results/sk/sk181079)

If you choose not to upgrade, Check Point can supply a **Hotfix** . [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 the Hotfix.  
For faster resolution and verification, please collect [CPinfo files](http://supportcontent.checkpoint.com/solutions?id=sk92739) from the Security Management Server and Security Gateways involved in the case.

**Hotfix installation instructions:**   
Refer to [sk168597 - How to install a Hotfix](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk168597).

<br />

---

# 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