If you try to perform the steps you give you will see that it is impossible, as there is no way to define reservations and the Local Network page has no DHCP server settings.
Fact is that you have to go to the bridge (when defining that for all LAN & WLAN clients) or port to set DHCP to Assign ... for known hosts only, and you have to define Network Objects for all clients to make this work.
If you look into the links at the end of you post you also will see that there is no procedure like the one given by AI, and i just wonder who has set it to Solution when it is neither documented nor does work at all...
I tend to only post solutions i have either tested/confirmed myself or found them in CP documentation or CheckMates dicussions (giving the reference for it).
CCSP - CCSE / CCTE / CTPS / CCME / CCSM Elite / SMB Specialist