Can't get Time Machine to work with Nighthawk

I purchased a Costco version of the 7900 series which is not listed in any Netgear documentation.  Tech Support doesn't even recognize the model number.  It's a Nighthawk X6S AC3600, R7960P-100NAS.  Firmware automatically updated to V1.0.1.34_1.0.20 when I installed the router with the iPhone app.  My external Segate 8TB Time Machine drive was working perfectly with a Time Capsule, but the wifi on the TC was poor, so I wanted to join the modern world and upgrade it.  So far, I've spent close to five hours with Tech Support, who take over my computer with Team Viewer, they have no idea how to operate a Mac, and they faff around coming to the same conclusion that I could have told them in 30 seconds, there is a fundamental problem with how they mount the USB drive that is incompatible with Time Machine.  This could be SMB, I can't get AFP to work.  I tried SMB on Mojave 10.14.4 as well as an older workstation running Mountain Lion 10.8.5.  The result is exactly the same, the drive mounts on the desktop but is not visible in the Time Machine menu of selectable drives.  It is notable that ReadyShare renames the drive, that is a red flag AFAIC.  I'm ready to give up and try another router.