Yes, and it didn't work. I then did an end-run by re-configuring the old DIR-880L as an internal LAN that was distinct from the DIR-X5460's LAN. After I plugged the USB drive into the 880L and attempted to mount it as an SMB drive, Windows 10 asked for a username and password, so I entered "Admin" and the 880L's admin password. The USB drive mounted without any problem and was also visible as a DNLA media server. I then plugged the USB drive into the X5460. When Windows asked for a username and password, I entered "Admin" and the X5460's admin password (which was the same as for the 880L), and Windows would NOT allow access. I was able to see the drive as a DLNA media server on a Windows computer that was connected to the X5460 with an ethernet cable, but not by another Windows 10 computer in my home that accesses the X5460 wirelessly. However, the Infuse Media Player program WAS able to access the USB drive as a DLNA server via wireless connections to the X5460, on both my iPhone and Apple TV set-top box. Based on that experiment, I suspect there is something wrong with the software in the X5460 that is preventing the USB drive from being mounted as an SMB drive. It seems there is also another software problem preventing the X5460 from providing a wireless DLNA server connection to a Windows 10 PC, but not to iOS and tvOS devices.
The DLNA server connections have been stable for about 36 hours, so I may leave it at that. The thought of trying to explain the problems to D-Link technical support personnel doesn't thrill me, as I expect they will blame Microsoft and tell me to wipe my Windows PCs, reinstall Windows 10, and start over.