Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/OpenAudio_ArduinoLibrary/src/commit/8ac9b2f5365cfc68eec7e51616939d20fed1edd7/examples/TestOutput_float You should set ROOT_URL correctly, otherwise the web may not work correctly.