Your ROOT_URL in app.ini is https://src.whiteboxsystems.nl/ but you are visiting http://src.whiteboxsystems.nl/Whitebox/u-boot/src/commit/18c534bbfbe9355fc5373547f4f89384a29da516/doc/README.VLAN You should set ROOT_URL correctly, otherwise the web may not work correctly.
upstream u-boot with additional patches for our devices/boards: https://lists.denx.de/pipermail/u-boot/2017-March/282789.html (AXP crashes) ; Gbit ethernet patch for some LIME2 revisions ; with SPI flash support
 
 
 
 
 
 
u-boot/doc/README.VLAN

551 B

U-Boot has networking support for VLANs (802.1q), and CDP (Cisco
Discovery Protocol).

You control the sending/receiving of VLAN tagged packets with the
"vlan" environmental variable. When not present no tagging is
performed.

CDP is used mainly to discover your device VLAN(s) when connected to
a Cisco switch.

Note: In order to enable CDP support a small change is needed in the
networking driver. You have to enable reception of the
01:00:0c:cc:cc:cc MAC address which is a multicast address.

Various defines control CDP; see the README section.