RAX120 new external hard drive not showing up

[douggold]

At the moment, I've got an old Time Capsule with a 1TB hard drive plugged into my RAX120 with an ethernet cable.  The Time Capsule's wifi featuers have been turned off.  I'm just using the 1TB hard drive it has for Time Machine to back up my macbook pro.  It works just fine.

But now I need more than 1TB for my backups.  I purchased this:

WD 8TB My Book Desktop External Hard Drive, USB 3.0 - WDBBGB0080HBK-NESN

I formatted it with my macbook pro and then plugged it into the RAX120's USB port, and... nothing.  It didn't show up on my macbook pro in any way.  What do I need to do to make it show up?

[plemans]

Is it a compatible device? 

https://kb.netgear.com/18985/Will-my-USB-drive-work-with-ReadySHARE

What format did you format it in? 

https://kb.netgear.com/24059/What-are-the-USB-drive-requirements-for-my-Nighthawk-router