@arnaudrigole That’s one way, albeit incredibly labor intensive.
Since you have a 2008 server, maybe you give a shot at setting a vendor class filter in it? There are some screenshots in the below article from 2008 to help you along your way, but I’ve not been successful yet. That’s not to say it can’t be done, it’s just saying it hasn’t been done yet. I was working on a community member’s production 2008 DHCP server and messed with it for a while but no luck. I’m not entirely sure his environment was even setup correctly…
If you are successful, we will be wanting screen-shots and steps for the Wiki.