R6400 readyshare stopped working

We've been using a seagate ext hdd for over a year (maybe two years?) via the back usb port as a readyshare drive. Had worked without troubles on wife's work computer (work's from home, win10) from day one until recently.  i had mapped it as the T: drive from day one. puter is connected to R6400 via ethernet cable. internet connection has never ceased.   

skip to the "summary" at the bottom if you want short version of where i'm  at, everything in between is the details of tests i've done so far, to develop that summary.

First round of troubles (included for to be thourough): a couple of months ago, wife's work computer suddenly couldn't connect to T drive.  I was at work. I had her unplugged drive, replug. no go. reboot router. no go. remove hdd and plug it directly in to computer's usb port. it worked, so she used in that fashion for the rest of the day. I got home, plugged it back in to the R6400. computer still did not connect to T drive, but I did see the readyhare folder available in the Network section of explorer. I removed old maping. remapped it and it worked fine again until ....

Second and present round of troubles: this week connection to mapped drive ceased again, readyshare was not available in network section of explorer. today I attempted some troubleshooting. 

    - (1) while monitoring network section of explorer as well as ready share section of netgear genie: unplug, replug hdd with computer and router on. (observation 1*) in netgear genie, drive went away and came back appropriately.  no connection to mapped drive nor presence in network section of explorer ever appeared, despite refreshes.

     - (2) plugged hdd directly in to usb port of computer. it blossomed as E drive, could be read fine.

     - (3) plugged hdd back in to R6400, same observation as (observation 1*) above

     - (4) wanted to reboot R6400, but noticed a firmware update was available. updated to V1.0.1.36_1.0.25, and let the reboot in this process count.  once back on same as (observation 1*) above

     - (5) just for fun, repeated step (1) and noticed something new. when I unplugged hdd from R6400 the 'media device' called "r6400" in the network section of explorer. went away, and came back when I plugged hdd back in.  (has this been happening all along and I didn't notice?!?! because it wasn't called readyshare?!?!).  when i double click this 'media device' called "r6400", it opens the 'basic' \ 'home' screen of  netgear genie in my browser (chrome). no access to files still.

     - (6) in netgear genie, if i 'edit' the readyshare device, and click the 'browse' button, a list of file folders does appear in the pop up window

     - (7) stuck....

soo....

summary:  the computer is connected to the router and has internet access. the r6400 can see and read the hdd just fine when plugged in. also when hdd is plugged in to the router computer sees a 'media device' in the network section of explorer called "R6400", but you can't access files via this. nothing else called "readyshare" in 'network' like there used to be.  hdd works fine when plugged in to computer directly.  

any ideas?  I really appreciate the help. 

Thanks,

Paul