Ok ... I have try it to add the Mac without the : and it works.
I have the Tutorial read, and read, and read again. But is not 100% clear that I only have the : to delete. But I'm a DSM Noob
please, can you give a clear answer to us what the correct format for Mac address in grub.cfg is ... please.
This: 64:00:6A:96:C3:07 or this: 64006A96C307
And second question, how can I find a tool/website for create a "real" Synology MAC and SN?