> Source: [sk152032](https://support.checkpoint.com/results/sk/sk152032)

# sk152032 - An SMB appliance behind a NAT device does not update the DDNS provider when the device's IP address changes

| Property | Value |
|----------|-------|
| Solution ID | sk152032 |
| Date Created | 2019-05-06 |
| Last Modified | 2022-07-21 |
| Technical Level | Advanced |
| Products | Spark Firewall (Locally Managed) |
| Versions | R81.10.X |
| Platform | 1570R, 1500, 1600, 1800, 910 |

## Symptoms

- Whenever the IP address of the NAT device (a device which is in front of the SMB appliance) changes, it is not possible to reach the SMB appliance using the DDNS service.

## Cause

SMB appliances update the DDNS provider only in the following scenarios:

* When the appliances connect to the DDNS provider for the first time
* Whenever the status of the Internet connection interface changes to 'Connected'

In other words, if the SMB appliance is behind a NAT device, and the IP of that device changes, then the DDNS provider will not be updated with the new IP address.

As a result, it will not be possible to reach the SMB appliance using the DDNS service.

## 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