With your patience, the example at: https://www.arduino.cc/en/Tutorial/Wifi101WiFiWebClientRepeating was supposed to show a 'working' example of a POST, not a failure. I assume from the code that the 'tutorial' was supposed demonstrate a working scenario reading back a text file on the Arduino website.
Yes, I understand 're-directs' are a fact of life, and the 301 may be the correct web response, but I still need a working set of examples of the MKR1000 and Arduino libraries that can POST, GET, and more. Have yet to see this MKR1000 and libraries function.
Am I supposed to fix the library, fix the Arduino website, or fix the tutorial?