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/2aa2bc444c769643e41cae5f17339cef91455e34/examples/BasicGain_Float You should set ROOT_URL correctly, otherwise the web may not work correctly.