Hello,
in the meantime I have debugged the coding and can tell that the request comes through the reverse proxy into the ABAP !
The request part is
/sap/opu/odata/UI2/PAGE_BUILDER_PERS/PageSets('%2FUI2%2FFiori2LaunchpadHome')?$expand=Pages/PageChipInstances/Chip/ChipBags/ChipProperties,Pages/PageChipInstances/RemoteCatalog,Pages/PageChipInstances/ChipInstanceBags/ChipInstanceProperties,AssignedPages,DefaultPage
See the picture from the debugger uploaded.
Now we stil have to find out, why it behaves differently when using the reverse proxy.
Regs
Ulf