Trying bridge nighthawk x4

> I've been trying bridge my old router nighthawk x4 to the ax12 [...]

   None of that is a model number.  Look for "Model" on the product
label(s).  Firmware versions?  What is connected to what?  (Hint: If a
device has different types of Ethernet ports, then "connected to device"
is not enough detail.)

   A bridge normally connects one thing to another thing.  Which two
things are you trying to connect?  How?  Why?

> [...] it doesn't seem want to connect correctly. [...]

   "it"?  "seem"  "want"?

   You might get further if you described actual objects and events in
the real world, and spent less time trying to describe the psychological
state of these devices.  What "it doesn't seem want" is at least two
levels removed from reality, and conveys no useful information (except
that you're unhappy).

   As usual, showing actual actions (commands) with their actual results
(error messages, LED indicators, ...) can be more helpful than vague
descriptions or interpretations.

> [...] Please help.

   You first?  Is there some actual problem which you are trying to
solve?