Onboard i225-V network controller not working properly

Hello,

I ordered a wonderful LattePanda Sigma with 32 GB und was very happy in configuring the installation of Windows 11 Pro.

But then I noticed a known Problem with the onboard Intel i225-V network controllers.

The problem is, that both network ports won't connect to a normal GBit-Switch.

I already tried all advices I found. The BIOS of the Sigma is the newest found here, tried different Intel drivers and also tried different settings like forcing the auto-negotiation to 1 GBIT Full-Duplex. But nothing worked.

In the first minutes of the NICs don't detect the connected network-cable, after this I may have luck, if they negotiated with 10 MBit/s.

Here are the articles from Intel:

https://www.intel.com/content/www/us/en/support/articles/000057261/ethernet-products/gigabit-ethernet-controllers-up-to-2-5gbe.html

https://www.intel.com/content/www/us/en/support/articles/000088564/ethernet-products/gigabit-ethernet-controllers-up-to-2-5gbe.html

I'm wondering about nobody else posted this problem here.

So, did i miss a known solution?

Greetings from Germany!