Posting on behalf of David Tseng:
Hi Javier:
Maybe you can try this: https://startingelectronics.org/tutorials/arduino/ethernet-shield-web-server-tutorial/web-server-LED-control/, or see Arduino's original Ethernet example:
Another way you can to is to get Arduino Yun(openWrt support), esp8266 or LinkIt 7697, they have better internet connectivity, Arduino compatible and can act as a web server.
For example, my App Inventor can interact with LinkIt 7697 like this, code attached.
use Web.get to call LinkIt 7697
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CAVEDU 教育團隊 / CAVEDU Education
曾吉弘 David Tseng
Phone: +886 931 087 928
Email: nis...@cavedu.com
Official website: http://www.cavedu.com
Blog: http://blog.cavedu.com
App Inventor 中文學習網: http://www.appinventor.tw