Intel I354 NICs only running in 100Mbit Mode

Hello Klaus Preisinger,

Thank you for reaching out to the community, Sophos Hardware appliance SG 135 rev.2 supports all current Sophos Firewall firmware versions.

So, you can upgrade it to SFOS, and can download the brand new firmware like SFOS v18.5.4 MR-4 - https://support.sophos.com/support/s/article/KB-000043162?language=en_US

Re-image the appliance - https://support.sophos.com/support/s/article/KB-000036812?language=en_US

You may Release Notes: https://community.sophos.com/sophos-xg-firewall/b/blog/posts/sophos-firewall-v18-5-mr4-is-now-available

https://docs.sophos.com/releasenotes/index.html?productGroupID=nsg&productID=xg&versionID=18.5

RMA Guide - https://community.sophos.com/sophos-xg-firewall/f/recommended-reads/134983/sophos-firewall-how-to-submit-an-rma-ticket-and-setup-the-replacement-firewall

From your focus on suggesting XG Environments, I take it that a SG solution is not available.

Hello Klaus Preisinger,

You can also download the latest build for UTM 9 hardware appliance - https://www.sophos.com/en-us/support/downloads/utm-downloads
And re-image the appliance - https://support.sophos.com/support/s/article/KB-000034331?language=en_US

In case of any difficulty in re-imaging process, feel free to revert us or contact Sophos Support !!

it is sadly not a latest update issue, it persists across many versions including the latest one as I have found out. 

then in which version, you are facing the issue ?

SG Hardware 9.711005

SG Software 9.711-5.1

Basically, the latest hardware and software versions both have this issue, pointing a problem concerning kernel support of the hardware. 

I am not sure which is the earliest version that the issue comes up. We discovered it by accident when the internet connection of the customer on eth0 was upgraded from 100Mbit to 250MBit. We could then verify the issue on another SG135rev2, meaning it is not an issue with just one piece of defective hardware. We also compared with a SG135Rev3, but since that is using the IntexX553 and Intel i211 chips, it remains unaffected.

Got it, can you shar system.log, fallback.log and kernel.log for the for kernel pointed issue. 

What does the Hardware Interfaces tab look like on your UTM as well?  Can you take a screenshot of that?

Interfaces & Routing > Interfaces > Hardware tab

Have you tried to force 1000MB on the hardware?