Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/MicroDexed/src/commit/5f92dd7844542bd328d2ab1e179168e49e4e7a6f/third-party/ArduinoJson/examples/JsonServer You should set ROOT_URL correctly, otherwise the web may not work correctly.