I have this great little W5100 break-out board / module which I've used already a lot in a project I'm working on with the Arduino Nano R3.
It works really nicely on the nano, runs very stable. I connect like this:
NSS > nano pin 10 MO > nano pin 11 MI > nano pin 12 SOK > nano pin 13 RST > +5v VCC > +5v GND > 0V
(info on the ebay auction says "run from 3.3v but data can run on +5v ok", however it clearly has a 3.3v regulator onboard and I've been running it fine from 5v)
However when I connect this up to my Mega 2560 I can't get it to work with my sketch.
I'm connecting of course to the Mega SPI lines, so;
NSS > mega 53 MO > mega 51 MI > mega 50 SOK > mega 52 RST > +5v VCC > +5v GND > 0V
I stripped my project back to basics and I'm testing by running the example sketch "Ethernet > Web Server" on a suitable IP address.
The lights on the W5100 breakout board seem ok, PWR and LNK are on, Rx flashes.
But I can't ping to the address, and serial monitor shows
server is at 0.0.0.0