Looking at this shield here: https://store.arduino.cc/arduino-ethernet-shield-2

It states that "Connection speed: 10/100Mb". However from looking at various forums it appears that no one can get much more than 300Kb/sec with this device?

Can anyone explain what causes this limitation and how to overcome it? If its SPI that is the bottleneck is there some alternative? I am looking to get speeds of 6 mega bytes per second or more using a TCP connection.

I am extremely new to all this so apologies if I've missed something extremely obvious here. I also had a look at bluetooth/wifi shields but it appears they seem to also have some similar throughput issues. USB looked like it could work but is extremely complex for a newbie.

  • If you have a caravan that is rated at up to 50 mph, and you attach it to a 50cc scooter, do you think you will be able to get the full 50 mph out of it?
    – Majenko
    Apr 20, 2019 at 18:05
  • Also: what do you want to do with all that data? Or how are you hoping to generate so much data so fast?
    – Majenko
    Apr 20, 2019 at 18:26
  • The data will be streamed from a PC into a games console, the stuff I am adding will sit in the middle
    – paulm
    Apr 20, 2019 at 18:27
  • "Sit in the middle"... what does that even mean?
    – Majenko
    Apr 20, 2019 at 18:29
  • @paulm According to your description, that PC is the best place to put that "man in the middle". However this is more like XY problem
    – KIIV
    Apr 20, 2019 at 19:05

2 Answers 2


It's not just the SPI what limits overall speed. You also need some proccessing power, and AVR based Arduinos lacks of it. It all depens what do you want to do with data.

If you need some serious processing power, it might be better to use something much more powerfull, like raspberry PI with real operating system. You can even run some web server at the speeds you can't even imagine with Arduino with the ethernet shield

  • 1
    Would it be possible to do it without needing a full blown OS? For just passing data between devices at higher speeds it feels like overkill?
    – paulm
    Apr 20, 2019 at 18:28
  • @paulm Of course it's possible. If you are a billion dollar company that Broadcom is willing to release the datasheet for the Pi's SoC to... And if you're a good programmer that understands all the underlying hardware.
    – Majenko
    Apr 20, 2019 at 18:32
  • Maybe FPGAs? Though it might be a really tricky and much work to program them for implementing ethernet.
    – chrisl
    Apr 21, 2019 at 16:14

A guy on this forum reports achieving 100 Kbyte/sec with a W5100 ethernet shield, which would be 800 kbit/sec:


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.