JWNR2010v5 Drop Out

> JWNR2010v5 [...]

   Firmware version?  Connected to what?

> My internet keeps dropping out. [...]

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual (at least).  Read.  Look for the
LED descriptions and "Troubleshoot"?

> I've tried downloading the latest firmware, but my Mac won't open the
> disk image ("not recognised").

   Try reading the instructions?

      https://community.netgear.com/t5/x/x/m-p/1721037#M124018

   Visit http://netgear.com/support , put in your 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.  (In the User Manual, look for "firmware", and,
especially, for a topic like "Manually Upload Firmware to the Router".)
When that fails because of a deficient User Manual, try:

      https://kb.netgear.com/23960

> [...] The netgear support website doesn't even recognise my router's
> serial number as valid. [...]

   With my weak psychic powers, I can't see what you're doing with what,
where, or any actual error message.  Note that a typical product label
includes a 12-character MAC address and a 13-character serial number,
and the placement of the captions is less than ideally clear.