Hi Steffen_ST,
Noticed your firmware version is 4.25, we have higher version 4.42 available on https://downloadcenter.intel.com/download/24769/NVM-Update-Utility-for-Intel-Ethernet-Converged-Network-Adapter-XL710-X710-Series
Please provide also information below:
1. ethtool <interfacename>’ with no additional arguments
2. fiber optic module model
3. cable make and model
Thanks,
wb