Thanks John,
I selected a series of device numbers in my 192.168.1 range that were not close to any of the 15 or so other device IPv4 addresses shown by my router. When I ran that batch file the NET USE /DELETE lines worked - those share are no longer mapped; but the lines to remap, using the selected IP addresses, failed. So I reverted to the original format for NET USE, with the account name and password, that had worked for me when entered manually. It seemed not to work at all, and no NAS shares are now mapped and visible. Some further research indicated that I need to create an "elevated shortcut" for the batch file, to enable it run as administrator in the STARTUP folder. I'm currently learning how to do that. If you have any further advice on this subject, I would be grateful.