ls-wvl940 issues with usb drive

[mattsky1]

Hello.  First time posting.   I have owned a ls-wvl940 since 2013.  It has a WD 1TB hard drive.  Monthly for the past 11 years, I connected a usb drive to the back port and used an app on my laptop to backup the hard drive to the usb drive.  Never an issue.  Today, I connected the usb drive and the function light illuminates steady blue, I loose access to the GUI interface, and windows explorer can't find the hard drive.  Remove the usb drive and all is well again.  Same issue occurs with a different usb drive.  The server is up to date on firmware and the usb drive functions normally when connected to a laptop.  I have not made any changes to the GUI settings.  Anyone know why I am suddenly having issues when connecting the usb drive.  I checked the manual and one description for a steady blue function light is "usb drive is dismounted" but not sure what that means given the usb drive works as expected when directly connected to a laptop.  TIA.