Thanks, but this didn't work.
I have compared the credential settings on the problem Window11 installation with those on another Windows11 PC I have.
Both have the same network information and settings. The network (router IP) is set as public on both. Shouldn't require a password to map a USB drive connected to that, my, router.
Both sets of Windows credentials for the router IP address are identical, I deleted and reentered those on the problem installation.
But I get the same result. When I try to map the drive (I have this mapped on two other platforms Windows 10 and 11, and never saw this username/password request on either when I mapped them) I get the The username or password is incorrect message again.
This should not be happening. Something is wrong if Windows security doesn't even recognize that the network it is accessing is simply a drive on the router that it, obviously, already has access to.
This is a brand new computer, with no bloatware. Only a new clean installation of W11 OME and a few programs I've added to play media files. There should be a straightforward way to fix this. If some buried setting is not set correctly, I didn't set it that way. Very frustrating.