Thank you for the post. Please ensure you are using latest driver and firmware for the NIC. The latest firmware is 5.05
You may use check the latest driver based on the OS used:
What is the brand and model of the fiber module connected to your XL710 ? Are the fiber module came with the network adapter?
We'd like to follow-up the information requested and kindly share the method of testing performed to measure the speed.
In case you're using windows operating system, please share to us the logs generated from system support utility.
system support utility download link: