Jovan Stosic– The W5100 board is a cheap version from china
– The resistor network immediately behind the Rj45 socket has the value 511 on it (its small get a magnifying glass – it is a black rectangle with 8 connections like a mini IC)
Basically it would appear this component is not correct. I should be 510 or close to this value. Because it is 10 times over spec it is much more sensitive to switches which are sensitive to the voltage on the network.
There are 3 possible fixes:
– Change to a switch that is not as sensitive. There is some discussion on the board about this.
– Change the resistor network to something close to the 49.9R that the arduino schematics suggest it should be. I have only seen one post where someone has done this and gotten it to work. This is fiddly due to the components being so small and surface mount … you would have to be keen to do this.
– Buy a more reputable brand wiznet board or switch to the even cheaper ENC28J60 boards which dont seem to have the same problems.
erroneous placement. A faulty connection occurs in particular at the when used as a Web client.
The incorrect line termination is apparent in reflections that prevent the connection.
I’ve tried everything, 4 different switches, short lines, long lines … the result was not satisfactory.
Short and sweet – my solution was quite simple:
1. Check to see if the SMD resistors are labeled 511 – see above (important)
2. Installation of two additional resistors 120 Ohm on the circuit side (Bottom Layer),
immediately in connection to the Ethernet jack. One between 1-2, and the other between 3-6.
The body of the resistors should point downwards so that no short circuit with the USB socket of the underlying UNO occurs.
The “1” of the socket is the way to the left (shorter distance to the edge) when the Ethernet socket facing upward, of course, on the ladder page (Bottom Layer) seen.The other terminals follow slightly offset.
After installation, I never had problems again …
I hope my Google English was understandable enough