Hello,

I am having some issues with the link between the switch and a workstation. I am using an SM5310-T(UN) 10G BASE-T SFP+ module and a 3M cat6a cable which connects to a Realtek 2.5GbE onboard network card.

When I connect both ends, the link comes up and the switch detects the link as 10G while the workstation detects the link at 2.5 when using auto-negotiation. After I shutdown the workstation or if it goes to sleep, the next time it comes up the link does not come up anymore. However I found that I can use the next port on the switch. It will come up at 10G on the switch and 2.5G on the workstation and everything works again. The next time the PC goes to sleep or is shut down I need to use the next port in the switch until I exhausted all free ports. If I then reboot the switch, I can use all ports again, once.

I tried everything from re-plugging the cable and sfp module, disabling and enabling the network adapter in Windows. The only thing that works, is setting the link speed on both the switch and the workstation to 1G. The link will then come up and gives a yellow light instead of green (1Gb instead of 10Gb). This will continue to work. Forever. Setting the speed back to auto-negotiation does not work. I also noticed that I can not set the switch port to 2.5G because it gives me a message that "it is not supported for fiber" even though I'm not using fiber.

Did I miss anything regarding compatibility? Do I need another SFP module? Or is the switch just not capable of doing 2.5G this and is the link coming up just luck.