How do I activate all 4 LAN ports on my router

> I purchased a new cable modem (Netgear Nighthawk CM1200) and a new
> router (Netgear Nighthawk RAX70). [...]

   Ok.  And did what with them?

> [...] Currently, only port 1 for LAN ethernet is working. [...]

   "only port 1" on _which_ device?

> [...] I cannot seem to get the other 3 ports to activate... [...]

   "seem"?  "cannot" is not a useful problem description.  It does not
say what you did.  It does not say what happened when you did it.  As
usual, showing actual actions (commands) with their actual results
(error messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

   Possibly relevant:

      https://community.netgear.com/t5/x/x/m-p/1770096