> Source: [sk183673](https://support.checkpoint.com/results/sk/sk183673)

# sk183673 - "Error: Failed to set MTU, because the maximum value allowed is 9702" when setting the MTU value on interfaces of Maestro Security Group Members

| Property | Value |
|----------|-------|
| Solution ID | sk183673 |
| Date Created | 2025-07-17 |
| Last Modified | 2025-12-08 |
| Technical Level | General |
| Products | Scalable Platforms |
| Versions | R81.20, R81.10 (EOS) |

## Symptoms

- * Unable to modify the Maximum Transmission Unit (MTU) values on the interfaces of Maestro Security Group Members (SGMs).

* After changing the MTU and rebooting an SGM, the interface comes online without its IP address configuration.

* Attempts to change the data interface MTU fail with the error:

  `Failed to set MTU, because the maximum value allowed is 9702`
* The /var/log/messages file contains errors similar to these:

  `
  Jul 11 01:06:55 2025 GCC-EQU-CPSG1-EPN-ch01-01 kernel:ethsBP1-01: Invalid MTU 9710`  
  ` requested, hw max 9702`  
  `
  Jul 11 01:06:55 2025 GCC-EQU-CPSG1-EPN-ch01-01 kernel:ethsBP1-02: Invalid MTU 9710 `  
  `requested, hw 
  `

## Cause

The issue occurs due to differences in hardware drivers across SGM appliances. Some interfaces support a lower maximum MTU value (for example, 9702). Configuring an unsupported MTU (such as 9710) causes the operation to fail and may result in the interface losing its IP configuration after a reboot.

## Solution

1. Run these `g_dbset` commands to set the MTU on backplane interfaces BPEth0 and BPEth1 to the maximum allowed value (9702):
   1. `g_dbset interface:BPEth0:mtu 9702`
   2. `g_dbset interface:BPEth1:mtu 9702`
   3. `g_dbset :save `
   4. reboot
2. Run these commands to verify that the MTU values were applied:
   1. `g_dbget interface:BPEth0:mtu`
   2. `g_dbget interface:BPEth1:mtu`
3. Configure the MTU on data interfaces:  
   Once the backplane MTU values are corrected, apply the supported MTU value (9702 or lower) on the data interfaces. Make sure the selected MTU is supported across all SGMs.

**Important Notes** :  

* These changes do not require a reboot.
* This issue may reoccur if a new SGM with a different network driver (and a lower MTU limit) is added to the Security Group.
* Installing a Jumbo Hotfix (JHF) or rebooting an SGM does not reset MTU values stored in the configuration database.

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