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/2118306ed95d5d468bf68fe9624aed2f8caee017/docs/bootstrap/img You should set ROOT_URL correctly, otherwise the web may not work correctly.