New OpenWrt install, slow performance

Installing and Using OpenWrt
1

I'm looking to move to OpenWrt as my primary router for a 1Gbps fiber service, moving off of Google Nest Wifi as my router. My speed tests to my ISP are consistently 800-900 Mbps.

I have OpenWrt 23.05.0 freshly installed on a TP-Link TL-WDR3600 v1 and it's seems to be running fine. When I use it as a switch (my PC and internal network both plugged in to the LAN ports) my speed is normal, 800-900 Mbps. As soon as I use as a router going through the WAN port, the speed drops to 200-300 Mbps.

I've tried the WAN port configured with PPPoE connected directly to the fiber box and using DHCP plugged in to the Nest Wifi, same results. Note that I have WiFi disabled, just using ethernet for now. I've checked the CPU load during testing and it's really low.

I installed iperf3 and running it from the SSH CLI also gives slow results, 200-300 Mbps.

Anything obvious I'm missing? I'm fairly new to OpenWrt so trying to keep the config as out of the box as possible to start with.

Technical details below...

|Model|TP-Link TL-WDR3600 v1|
|Architecture|Atheros AR9344 rev 2|
|Target Platform|ath79/generic|
|Firmware Version|OpenWrt 23.05.0 r23497-6637af95aa / LuCI openwrt-23.05 branch git-23.236.53405-fc638c8|
|Kernel Version|5.15.134|

Speedtest results (speedtest CLI on Mac):
(in switch mode only using LAN ports)


   Speedtest by Ookla

      Server: Gosfield North Communications - Cottam, ON (id: 11505)
         ISP: Gosfield North Communications Co-operative Limited
Idle Latency:     2.12 ms   (jitter: 0.04ms, low: 2.04ms, high: 2.14ms)
    Download:   898.97 Mbps (data used: 450.2 MB)                                                   
                 19.62 ms   (jitter: 1.53ms, low: 1.74ms, high: 50.11ms)
      Upload:   825.40 Mbps (data used: 381.9 MB)                                                   
                 16.50 ms   (jitter: 1.78ms, low: 2.08ms, high: 23.20ms)
 Packet Loss:     0.0%
  Result URL: https://www.speedtest.net/result/c/506dd2aa-5d37-4993-a8da-df4173a79476

(in router mode, using DHCP or PPPoE on the WAN port)

   Speedtest by Ookla

      Server: Gosfield North Communications - Cottam, ON (id: 11505)
         ISP: Gosfield North Communications Co-operative Limited
Idle Latency:     2.20 ms   (jitter: 0.12ms, low: 2.03ms, high: 2.34ms)
    Download:   282.65 Mbps (data used: 247.3 MB)                                                   
                 11.21 ms   (jitter: 1.52ms, low: 3.10ms, high: 38.57ms)
      Upload:   146.90 Mbps (data used: 127.9 MB)                                                   
                 20.94 ms   (jitter: 6.08ms, low: 4.47ms, high: 234.79ms)
 Packet Loss:     0.0%
  Result URL: https://www.speedtest.net/result/c/a7b75b4a-8037-4b7a-a274-dec4cc723687

iperf3 results with my PC wired directly to the router

Connecting to host 192.168.86.35, port 5201
[  6] local 192.168.86.58 port 54900 connected to 192.168.86.35 port 5201
[ ID] Interval           Transfer     Bitrate
[  6]   0.00-1.01   sec  25.9 MBytes   216 Mbits/sec                  
[  6]   1.01-2.00   sec  26.6 MBytes   224 Mbits/sec                  
[  6]   2.00-3.00   sec  22.9 MBytes   191 Mbits/sec                  
[  6]   3.00-4.00   sec  23.1 MBytes   194 Mbits/sec                  
[  6]   4.00-5.00   sec  25.9 MBytes   217 Mbits/sec                  
[  6]   5.00-6.00   sec  25.4 MBytes   214 Mbits/sec                  
[  6]   6.00-7.00   sec  27.5 MBytes   231 Mbits/sec                  
[  6]   7.00-8.00   sec  23.1 MBytes   194 Mbits/sec                  
[  6]   8.00-9.00   sec  23.0 MBytes   192 Mbits/sec                  
[  6]   9.00-10.00  sec  25.6 MBytes   215 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  6]   0.00-10.00  sec   249 MBytes   209 Mbits/sec                  sender
[  6]   0.00-10.01  sec   249 MBytes   209 Mbits/sec                  receiver
2

iperf running on the device is often not a good representation of the maximum routing speed because many routers do not have powerful main processors (instead, they have highly specialized routing hardware).

However...

That's not all that surprising. The device you have is actually quite old -- it seems to date back to 2012. The single core 560MHz processor is likely the bottleneck here -- it probably cannot route anywhere near 1Ggbps (very few consumer devices of this era could even reach 500Mbps).

Your Google Nest wifi is much much more powerful, and this should be your main router.

If you want to move to OpenWrt, you will need a more powerful device -- likely something made within the last few years.

EDIT: Also worth stating -- OpenWrt is not the main bottleneck here -- it is the hardware. To prove that, you could reinstall the stock firmware for that device. It is possible you may experience slightly higher bandwidth if the stock firmware has special optimizations that OpenWrt lacks, but this won't get you anywhere near 1Gbps.

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3

You'll never achieve gigbit speeds using that device, and Openwrt.

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4

Thanks @psherman @frollic I didn't realize gigabit required such high performance hardware. I'll stick to the Nest Wifi for now and look for newer hardware for OpenWrt eventually.

I had this router in a drawer for a few years and had the idea of making it useful, oh well!

Thanks for the quick reply!

5

Understood. That device could certainly serve as a platform for you to play with and learn OpenWrt... especially if you want to start exploring VPNs, VLANs, or other advanced concepts. It'll work well for those tasks (operating behind your main router such that it doesn't cause a bottleneck for the main network).

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