copy files from PC to NAS

[OldYogi]

My primary music library is on my PC, maintained with MM. I loaded that library on an external usb hard drive ("HD") and then attached that HD to my Asus RT-AC68U wifi router. The router then set it up as a DLNA server. Works fine. MM finds the router, and identifies the router as a media server. I can access it and play music from it over wifi from any PC in the house running MM.

When I add new music to the library on my PC I'd like to be able to copy it to the HD attached to the Router.
Windows7 recognizes the router as a network device, but doesn't assign a drive letter. So I can't copy directly using Windows copy.
In MM, under Tools>Options>Portable Audio devices the HD doesn't appear.

I suspect this is not really a MM problem,but a windows or router problem, but any suggestions would be appreciated.

[Lowlander]

The device should be accessible with its UNC Path (something like \\DeviceName\folder). You can move files to that path using Tools > Auto-Organize Files on selected files.