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Slow TX speed on 2.5G LAN


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Hello everyone!

 

I have a 2.5gb LAN in home but when I found some strange issues when testing the connection speed with iperf3:

 

Running iperf3 as a server on my Unraid machine gives me full speed:

-----------------------------------------------------------
Server listening on 5201
-----------------------------------------------------------
Accepted connection from 192.168.1.5, port 35508
[  5] local 192.168.1.11 port 5201 connected to 192.168.1.5 port 35510
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   1.00-2.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   2.00-3.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   3.00-4.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   4.00-5.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   5.00-6.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   6.00-7.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   7.00-8.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   8.00-9.00   sec   280 MBytes  2.35 Gbits/sec                  
[  5]   9.00-10.00  sec   280 MBytes  2.35 Gbits/sec                  
[  5]  10.00-10.00  sec   488 KBytes  2.25 Gbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.00  sec  2.74 GBytes  2.35 Gbits/sec                  receiver

 

When I set Unraid to be the client, I got half of the expected speed:

Connecting to host 192.168.1.5, port 5201
[  5] local 192.168.1.11 port 58342 connected to 192.168.1.5 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   140 MBytes  1.17 Gbits/sec  668    294 KBytes       
[  5]   1.00-2.00   sec   136 MBytes  1.14 Gbits/sec    0    294 KBytes       
[  5]   2.00-3.00   sec   134 MBytes  1.12 Gbits/sec    0    291 KBytes       
[  5]   3.00-4.00   sec   136 MBytes  1.14 Gbits/sec    0    297 KBytes       
[  5]   4.00-5.00   sec   134 MBytes  1.12 Gbits/sec    0    294 KBytes       
[  5]   5.00-6.00   sec   134 MBytes  1.12 Gbits/sec    0    303 KBytes       
[  5]   6.00-7.00   sec   136 MBytes  1.14 Gbits/sec    0    297 KBytes       
[  5]   7.00-8.00   sec   138 MBytes  1.15 Gbits/sec    0    294 KBytes       
[  5]   8.00-9.00   sec   132 MBytes  1.11 Gbits/sec    0    297 KBytes       
[  5]   9.00-10.00  sec   134 MBytes  1.12 Gbits/sec    0    303 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  1.32 GBytes  1.14 Gbits/sec  668             sender
[  5]   0.00-10.00  sec  1.32 GBytes  1.13 Gbits/sec                  receiver

 

Tested with another iperf3 server returned the same result. The dashboard gives me 2500Mbps full duplex on network interface, since it's an onboard ethernet port I'm not able to switch the card for testing. My motherboard is ASUS TUF GAMING B550M-PLUS WIFI II if that helps...

 

Could anyone help me to fix it, or any ideas to move forward on debugging this?

Thanks for the help and thanks for reading

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  • 4 weeks later...

I have the same issue of the download speed with Realtck 2.5g NIC.

If I disable the bridging of the NIC. The download speed from Unraid goes back to normal (280 MB/s). But if I enable the bridging of the NIC, the speed becomes to half (140 MB/s) again.

Should it be a bug of Unraid?

  • Like 1
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  • 2 weeks later...
On 6/5/2022 at 11:26 PM, defender said:

I have the same issue of the download speed with Realtck 2.5g NIC.

If I disable the bridging of the NIC. The download speed from Unraid goes back to normal (280 MB/s). But if I enable the bridging of the NIC, the speed becomes to half (140 MB/s) again.

Should it be a bug of Unraid?

 

Oh my god you just saved my day! I turned off the bridging and it's now running at full speed both ways! Now my solution is to use a cheap USB ethernet dongle for bridging only to release the onboard 2.5Gb LAN.

 

It seems the docker bridge won't effect the network speed on my machine, so it might because of something related to virtio-net?

Edited by kenpuluma
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