Does anyone know if there is an Ethernet shield is compatible with the Arduino Ethernet shield (R3)? The R3 does not seem to be in production anymore and I need a replacement shield. Found some from Velleman, or maybe Ethernet Shield 2?
No, it is not compatible. It uses the ENC28J60 chip from Microchip, whereas the others all use the W5100 Wiznet chip. A very different chip.
You can use it if you refactor all your code to use the Ethercard library instead of the Ethernet library.
There are cheap Chinese (or other far east) clones of the Ethernet Shields, that use the W5100 (or a counterfeit copy) that people have varying amounts of luck with if you really need W5100 compatibility. I have one, but have had problems with it starting up properly sometimes and needs a bit of a kick with the reset button.