Hi,
I found an alternative solution from a 2014 topic that seems to work fine.
It came from this topic Dataprocessor + Gantt -> Save on demand from a @Stanislav answer
You can do this to send to your server side tasks and links in 2 requests
dp.setGanttMode(“tasks”);
dp.sendData();
dp.setGanttMode(“links”);
dp.sendData();
Hope it helps