Where can I get the latest firmware for RN171 and how can I upgrade it?
RN171/131/1723 firmware is posted on the Microchip FTP site (details in the "WiFly Command Reference Manual"). Those modules are capable of fetching the firmware files from our FTP site, given it is connected to access point with an internet connection.
There are multiple ways to upgrade the RN171 firmware, the right method depends on what firmware version you have and what resources you have at your disposal. Detailed instructions on upgrading firmware can be found in the "WiFly Command Reference Manual" located under the 'Documents' section of the landing page for the module you are using.