> Source: [sk166978](https://support.checkpoint.com/results/sk/sk166978)

# sk166978 - DHCP does not work when the DHCP server is behind the VPN peer on SMB appliances 

| Property | Value |
|----------|-------|
| Solution ID | sk166978 |
| Date Created | 2020-05-29 |
| Last Modified | 2024-03-13 |
| Technical Level | General |
| Products | Spark Firewall (Locally Managed) |
| Versions | R81.10.X |
| Platform | 1500, 910 |

## Symptoms

- * DHCP does not work when the DHCP server is behind the VPN peer. However, the traffic looks like it is making it to the peer and the response is confirmed.
* Security logs show drops for "`Connection contains real IP of NATed address`" that is dropping on outbound (the source is Gateway LAN IP).
* "fw zdebug drop" shows:

  ```
   
  ...Packet proto=17 x.x.x.x:67 -> y.y.y.y:67 dropped by fw_conn_inspect Reason: post lookup verification failed;
  ```

  Where x.x.x.x is the DHCP server and y.y.y.y is the local LAN Gateway IP.

  <br />

## Solution

In **Advanced Settings, Device** \> search for **dhcp** \> edit DHCP relay to **Use internal IP addresses as source** .   

Make sure this is unchecked, then click **Apply** .  

![](https://sc1.checkpoint.com/sc/SolutionsStatics/sk166978/dhcp_setting120200519083803.png)  

In the same **Advanced Settings** page, search for **internal** and edit **VPN Site to Site global setting** - **Use internal IP address for encrypted connection from local gateway** \>**Edit**   

Make sure this option is checked.  

![](https://sc1.checkpoint.com/sc/SolutionsStatics/sk166978/internal20200519083844.png)

<br />

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