C7100v Cannot change DNS server

[Brewc53]

I’m using unlocator with MLB tv on Apple TV, have used it last 3 seasons worked fine.
Had problems getting it to work as I can’t use the two DNS they tell me to use they won’t save in the Netgear setup when logging in from computer.
Supposed to use 185.037.037.037 and 185.037.039.039 and they say invalid.
I have an old Apple AirPort Extreme I tried it on and can change them, they save, why is it I can’t with this Netgear?
Bought this 4 months ago to quit paying Comcast rental fees and it’s just been a headache, first not being able to use the USB port to hook external drive for backup and now this!

[antinode]

> I'm using unlocator with MLB tv on Apple TV, [...]

   On what device?  Can you specify the DNS server(s) on that device
itself (instead of on the router)?

> Supposed to use 185.037.037.037 and 185.037.039.039 [...]

   Did you try without the (should-be-harmless) leading zeros?
("185.37.37.37", for example?)

> [...] they say invalid. [...]

   What's the actual error message?  There have been some similar
reports here involving Cxxxx models.  A forum search for the actual
error message might find them.

   As I recall, no one has yet determined whether the problem lies with
the modem+router firmware or restrictions imposed by the ISP.

> [...] not being able to use the USB port to hook external drive for
> backup [...]

   That's not much of a problem description.