@SpongeBen 

Hi,

May we know the make and model of your Internet modem?

Not all 10 Gbps Ethernet ports support the intermediate speeds 5 Gbps and 2.5 Gbps. Some 10G networking equipment only supports the grades 10 Gbps / 1 Gbps / 100 Mbps / 10 Mbps.

  @terziyski 

Thank you for your reply. 

My GE550 ethernet status / port negotiated speeds:

Let me know if you want to know more about my GE550 configuration. Thanks!

  @woozle 
Thank you for your reply.
My model of Modem is: Huawei OptiXstar HN8250Ts-20 XGS-PON Terminal

I have tested the internet speed with the router and got 5 Gbps.

Also, I got 5 Gbps when I connected my computer and modem directly. Therefore, I think my modem should support 5 Gbps. 

Let me know if you want more information. Thank you!

  @SpongeBen 

Thanks. Yes, on the one screenshot we can clearly see that the GE550 has negotiated 5 Gbps links to the modem as well as to the TX401. So that is all good.

Have you already tested if the Speedtest on your computer can get up to 2.5 Gbps when the TX401 is connected to one of the GE550's 2.5 Gbps LAN ports?

Also, in case you have any sort of "QoS" activated on the GE550, then switch it off for a test.