I recently bought a USB 2.5Gbps ethernet adapter to give a little boost to my UnRAID server, seeing my computer and switch are already 2.5Gbps capable.

 

The adapter have a Realtek RTL8156B chip, so I installed the drivers in UnRAID through "Apps", and put it as eth0. Apparently working fine, and recognised as a "2.5Gbps" link in UnRAID.

 

Problem appears when I see soemthing strange is happening: when running tests in UnRAID, it caps out at 1.4Gbps always. I don't know why.

 

The strangest thing? If I run the iperf3 server in my computer (so reversing, instead of iperf3 server in Unraid, now UnRAID is the client to my computer server) then the speeds are not "capped" and seems to be able to do fine.

 

Running OpenSpeedTest in Unraid also caps at 1.4Gbps both download and upload.

 

I see the switch and cables are fine, Realtek drivers installed, I tried both NIC Offload ON/OFF to little effect...

 

Anyone has any idea or tips? Thanks

 

*This is the iperf3 output from UnRAID (running the measuring speed test in UnRAID = hard cap at 1.4Gbps; running it in computer = about 2Gbps):

 

Quote

root@UNRAID-SERVER:~# iperf3 -c 192.168.X.X
Connecting to host 192.168.X.X, port 5201
[  5] local 192.168.X.X port 42770 connected to 192.168.X.X port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec   241 MBytes  2.02 Gbits/sec  14958    361 KBytes       
[  5]   1.00-2.00   sec   239 MBytes  2.00 Gbits/sec  14134    416 KBytes       
[  5]   2.00-3.00   sec   240 MBytes  2.01 Gbits/sec  15304    421 KBytes       
[  5]   3.00-4.00   sec   233 MBytes  1.96 Gbits/sec  14692    645 KBytes       
[  5]   4.00-5.00   sec   237 MBytes  1.99 Gbits/sec  16984    421 KBytes       
[  5]   5.00-6.00   sec   243 MBytes  2.04 Gbits/sec  13072    410 KBytes       
[  5]   6.00-7.00   sec   239 MBytes  2.00 Gbits/sec  12153    413 KBytes       
[  5]   7.00-8.00   sec   239 MBytes  2.01 Gbits/sec  16754    421 KBytes       
[  5]   8.00-9.00   sec   238 MBytes  2.00 Gbits/sec  13519    407 KBytes       
[  5]   9.00-10.00  sec   239 MBytes  2.00 Gbits/sec  17033    378 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  2.33 GBytes  2.00 Gbits/sec  148603             sender
[  5]   0.00-10.00  sec  2.33 GBytes  2.00 Gbits/sec                  receiver

iperf Done.
root@UNRAID-SERVER:~# iperf3 -s
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------
Accepted connection from 192.168.X.X, port 49219
[  5] local 192.168.X.X port 5201 connected to 192.168.X.X port 49220
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   164 MBytes  1.37 Gbits/sec                  
[  5]   1.00-2.00   sec   169 MBytes  1.42 Gbits/sec                  
[  5]   2.00-3.00   sec   170 MBytes  1.42 Gbits/sec                  
[  5]   3.00-4.00   sec   171 MBytes  1.43 Gbits/sec                  
[  5]   4.00-5.00   sec   171 MBytes  1.43 Gbits/sec                  
[  5]   5.00-6.00   sec   170 MBytes  1.43 Gbits/sec                  
[  5]   6.00-7.00   sec   170 MBytes  1.43 Gbits/sec                  
[  5]   7.00-8.00   sec   170 MBytes  1.43 Gbits/sec                  
[  5]   8.00-9.00   sec   170 MBytes  1.43 Gbits/sec                  
[  5]   9.00-10.00  sec   170 MBytes  1.43 Gbits/sec                  
[  5]  10.00-10.05  sec  8.12 MBytes  1.41 Gbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.05  sec  1.66 GBytes  1.42 Gbits/sec                  receiver
 

 

If you have bridging enable try disabling it, seem to remember it could slow down some Realtek chips in one direction.