As you can tell, this chip is made by Microchip, and it's also the chip that they used to make the Arduino WiShield as well. Unfortunately, the TCP stack they had for the Arduino ( WiShield library ) stopped working with the new revs of the chips. Not sure if this was deliberate from Microchip or what. They literally took out some of the command that stack was based on. The WiShield stack wasn't very reliable anyway ( no TCP checksum, etc ... ) because it was designed to run on the Atmega328, which has very little SRAM. So ... if this was an earlier rev of the chip, what you would have had to do is to use an Arduino compatible core, and hook it up to the SPI pins on that core, and straighten this out. Now, with the new chip, you have to download Microchip's TCP stack and write yourself a HAL layer to more or less emulate the SPI interface and jiffies of the Microchip's PICs that the stack is designed to work with. The Microchip stack if full fledged and very reliable. But that's quite the project. Hope this helps.