Hi everybody,

I recently got my first NAS with Unraid. It i an Aoostar Wtr Pro with 1 HDD and 1 NVME as a cache. Both my computer and NAS are connected to a 2.5Gb switch.

My issue is that I cant reach full upload speed to my NAS. Download however is fine.

I tested my drives first. They are working with the expected speed.

Then I tested with OpenSpeedTest and iperf the speed between my NAS and computer:

There seems to be a bottleneck.

So I changed the cable and the switch -> no improvement.

Then I directly connected my NAS to my computer with a static IP -> also no improvement.

I bought a usb-c to 2.5Gb dongle to see if this improves the speed somehow.

Is this maybe a settings issue within Unraid?

Thanks for your help already!

Edited December 9, 2025Dec 9 by M4ks
Posted to early by accident

likely you are a victim of the famous "2.5G needs Flow Control" issue.

See if flow control is enabled on both ends and in the switch.

if not, a new connection often pick the wrong sending window and it is not received by the other side. After a timeout it is retried within a different window. This can slow down a connection up to 75% (but usually it is only 50%)

Hey, thanks for the reply.

I updated the my network driver and enabled flow control which fixed it for me!

Thanks a lot!