Your ROOT_URL in app.ini is https://src.whiteboxsystems.nl/ but you are visiting http://src.whiteboxsystems.nl/Whitebox/u-boot/blame/commit/ab8243e43145598a55182c3f8ba0784f70526358/configs/P2041RDB_SDCARD_defconfig
You should set ROOT_URL correctly, otherwise the web may not work correctly.