Have you noticed the bits highlighted in red?

Slotting/100% WOC is tough on machines. Having 25mm tool stick out (length should be the distance the cutter protrudes from the collet/holder) is the main killer in those figures. If you reduce tool length to 15mm, DOC increases significantly.
However, whether you can achieve that will depend on the overall rigidity of your machine, and the figures produced by any F&S calculator should be treated as starting point. Some machines will be able to run harder, some will need to run slower, so you'll still need to experiment for your particular machine, material, and cutters.