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/42b5fda1eb0b24c2d0c72de8231207bbe22191b6/examples/BasicGain_Float
You should set ROOT_URL correctly, otherwise the web may not work correctly.