VPN connection error with MTU?

[PeterLin]

Hello,

Hi,

I found sometimes that my VPN session is disconnected and shows an error prompt, and I need to reconnect manually.  From the DART log, there is an error message as below:

A new MTU needs to be applied to the VPN network interface. Disabling and re-enabling the Virtual Adapter. Applications utilizing the private network may need to be restarted.

Can someone help to solve this error?

Thank you.

[M02@rt37]

Hello @PeterLin 

Ensure that you are using the latest version of the VPN client. The issue could be caused by a bug or a known issue that has been fixed in a later version.

Also, the "recommended value" for MTU is 1400 bytes. This value is often used because it provides a safe buffer for overhead and avoids fragmentation on most networks, while still allowing for efficient data transmission. But MTU value may vary depending on the network environment and the type of VPN connection being used.

[PeterLin]

Thanks for your reply!

The version of AnyConnect I am using is 5.0.00556.

Yes, the MTU value seems depend on the network environment. I dig more into the DART logs and find that the disconnection was caused by below error:

Description : Termination reason code 12:

Initialization failure (mem alloc failed, etc.).

Seems that the VPN session need to re-establish because a new value of MTU ​was applied, but there was an initialization error (mem alloc failed, etc.) , then makes the VPN disconnection. 

Any idea about this error Termination reason code 12: Initialization failure (mem alloc failed, etc.) ?

Thanks.

[M02@rt37]

Hello @PeterLin 

Is there any other software that may conflict with the VPN client, such as firewalls or antivirus software ? 

Also, if the MTU value is causing the issue, you can try adjusting the MTU settings on your device or VPN client to see if this resolves the issue.