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/f5d1c01a588f31d7abc4913c81c109d8aa006be7/examples/PassthroughF32 You should set ROOT_URL correctly, otherwise the web may not work correctly.