Did some more testing on this, and found the following:
--hooked up my old WD TV Live with the exact same network cable as I use with the Mede8er and still got the weird extra : 1 with "Generic DLNA." I did this to make sure it wasn't the Mede8er itself.
--installed the last version of MC22, restored my library, and everything worked perfectly: no : 1, only "Generic DLNA" as it's been.
So it's probably not my computer, my router, nor my cabling. Since the only thing that's altered since last week is the version of the 64 bit MC23 (and some cumulative Windows 10 updates, though I doubt these are the issue), and since there were some DLNA-specific alterations, I'm guessing there's something funky with DLNA in the most recent version or two of MC23 64 (72 and maybe 70, too), at least on my system.