In the interim I gave AirDroid a shot. pretty clever - sort of like using teamviewer et al if my suspicion is correct. would not hold a connection using FFox "nightly" x64, but using Chrome it works. a bit clumsy, as my brain prefers regular windows-looking folders, details mode, serial lists, with most of the columns showing data
ES File Explorer, the latest/current version, has no field for Computer Name. It will scan, identify the pc's on the net by IP, and the detail fields are:
Server [meaning IP address]
tickbox for "Anonymous"
that's all. I tried then inserting the PC name into the Username field per your instructions and it failed.
Put in the Username and correct password and it also failed.