Orbi RBR760 DHCP Option 61 Special Character Input Client Identifier Field

My guess is that front line Customer Support staff are not equipped to handle this issue:

• They open the User Manual and it simply says to enter what the ISP provided.  From the web page (show page in Chrome) it is obvious that a 20 character input box is displayed and that the entry can be up to 64 characters.  On the RBR50 and RBR750, the description is "text".  Nothing in the User Manual or the "Help" screen says anything about prohibited characters.
• I have no idea how many ISPs require DHCP Option 60/61.  I know that Spectrum does not.  They may never have received a call about this, and thus whatever database they query has no information.
• They do not have a room full of Orbi systems to experiment with, and (again my guess) they are expected to be talking to customers and not conducting tests and experiments.
• If the issue got escalated to someone more senior, perhaps they could connect to a 760 and reproduce the problem.

If this was purchased from a vendor with a liberal return policy, I'd return it and buy something else.  If it came directly from Netgear, a return may be more complicated.