Failed to connect with Arduino Ethernet Board (not shield) - help please

Hi everyone,

I’m a totally frustrated beginner. I’ve managed to run the simple example sketches (Blink, Tone, etc) on my Arduino Ethernet, also managed to connect it through a breadboard with simple circuits to turn on/off LEDs and PC fans etc. BUT I can’t seem to get the Ethernet sketches to work at all!

The instructions/tutorials I’m following are all unclear to me and these are my general questions (pardon me but they’re very basic!):

  1. Should I power my board with the adapter instead of through the USB/FTDI? If yes, should I upload the sketch, then disconnect USB, then plug in adaptor? Or, how should I do it?

  2. I plug in one end of my ethernet cable into the board. Where should I plug in the other one? I tried plugging the other end to my router. I ran WebClient sketch. Opened the serial monitor. Didn’t work (failed to connect). I tried plugging in to my MacBook Pro. Ran the sketch. Didn’t work (same result).

  3. Should I change the MAC address in the sketch? I saw a YouTube example where the MAC address was not touched at all. Tried that, didn’t work (failed to connect). Then I tried putting my laptop’s MAC address (following the instruction at - the compiler stopped while processing my MAC address (“error: ‘d9’ was not declared in this scope”). Then I read somewhere that there’s supposed to be a MAC address on a sticker on an Arduino Ethernet Shield - so I looked at it and found a sticker with a series of numbers which could fit into the MAC format … similar error to when I put my laptop’s MAC address in. What should I do?

  4. Should I change the IP address in the sketch? I tried putting my laptop’s IP address in - error. I tried not changing the IP address in the sketch - failed to connect. I tried putting, (got these from one random example) - still failed to connect.

  5. Should I disconnect my laptop from my wifi connection before attempting to run any of the sketch? I mean, if I have a wifi connection, would that disrupt the supposed Ethernet connection? It’s all very confusing.

Could someone please help me and let me know what I should do? Or, if I’m not asking the right questions, or not asking the questions the right way, could you please let me know how to ask?

Thanks a million.