NETGEAR Nighthawk Cable Modem & ATT Uverse

> [...] I purchased the netgear nighthawk X6S router. [...]

   None of that is a model number.  Look for "Model" on the product
label.

> [...] My u-verse router is 7 years old. [...]

   Aside from its age, I know nothing about it.  Maker?  Model number?

> [...] So is my u-verse modem. [...]

   Aside from its age, I know nothing about it.  Maker?  Model number?

> [...] I'm not anticipating any problems when i get my new netgear
> CM1200 modem.

   That's nice, but no one here was predicting any problems with
communication between any modem and any router.  The concern is about
communication between a cable modem and your ISP.  With no useful
information about your "my u-verse modem", the non-psychics in your
audience are left to guess at what might be compatible with your
service.

   And the current guesses are that you might want to anticipate some
problems.