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/198ae0d33595676724814882a444f4877542264f/examples/FormantShifter_FD_OA You should set ROOT_URL correctly, otherwise the web may not work correctly.