Nighthawk AC1900 cuts internet speed in half from wired modem

> Nighthawk AC1900 [...]

   "AC1900" is a speed, not a model number.  Look at the product label.

> Model: A7000|Nighthawk AC1900 WiFi USB Adapter - USB 3.0

   Not a router.

> [...] cuts internet speed in half from wired modem [...]

   From what to what?  Actual numbers would be more interesting than "in
half".

> I have read the message traffic [...]

   Thanks for the helpful links.  _Which_ "the message traffic", where?

> [...] I do not see this version on the Netgear support page. [...]

   _Which_ "the Netgear support page"?  Where did you look?

> Where do I find this version or lower?

   Visit http://netgear.com/support , put in your (actual) model number,
and look for Downloads.  (For older versions, under Firmware and
Software Downloads, look for "View Previous Versions".)  Find the
kit(s).  Download the kit(s) you want.  Read the "Release Notes" file
for instructions.

   Assuming that you have an R7000, you might first try 1.0.9.42, before
going back so far as some 1.0.7.x version.

> Are there any other fixes out there besides downgrading the firmware
> version?

   That might depend on what the cause of the problem is.  A Web or
forum search for terms like "slow" might find any number of suggestions.