Hey folks,

I'm running unraid 6.9.2 on my previous ITX PC, it has 2.5 GbE NIC connected via 10GbE switch to my PC which also has 2.5 GbE NIC,
now iperf3 from unriad to my PC saturate 2.5 Gig connection without issues on just 1 iperf stream.
But iperf3 upload from my PC to unraid is floating around 500-300 Mbps on a single iperf stream, if I run multiple iperf streams with say -P 8 I can saturate 2.5 Gig link.

Any suggestions where I should look for problems? Initially when I first setup this server a couple days ago I was transferring data to my (non cache backed) array (2x 4TB disks) I saw ~1.3 Gbps direct to array speeds, since initial setup I just added 3 docker containers:
Portainer, html speed test and unifi controller (connected to br0 custom with it's own IP). Stopping docker service has no impact.

Server specs:
Ryzen 5 2400g, 32GB RAM, 2x 4TB HDD in array, 1x 500GB NVME - unused atm, 1x 160GB SSD unused atm

BTW transfers to NVME or SSD shares show same behaviour 1 stream is limited to ~300-500 Mbps

Edited December 22, 20214 yr by canni86

Try with a different PC if available, could also be the Windows install, i.e., try a new one on a new disk/ssd, or could also be just a NIC driver/setting issue.

I tried from my wife's iMac, it only has 1 gig NIC, and i'm also seeing ~300-500 Mbps upload speed from there.

To eliminate my PC (and switch), I ran iperf tests between my PC and my router, although router's NIC is only 1 gig I could saturate this connection both ways.
This is super strange, as just days ago I saw ~1.3 Gbps (140-150 MB/s) transfers from my PC to unraid on my initial data migration.

(I'm testing transfer speeds with iperf3 and ~4GB windows/linux ISO files to ignore small files impact)
Also some forum digging suggested to turn of NIC offloading from Tips and Tricks, this had no impact, I also tried Fix common errors plugin, no luck there too.

After very long debugging session, recreating the whole unraid server from scratch, a reboot of client machines (PC and iMac) helped, go figure ...