The server is a Debian box that’s wired to the network, and Ping works.
I pretty much already had what the “dummies” book said I needed set up, except for the All Networks setting. That didn’t seem to change anything.
But it turns out that there’s a setting that allows you to enable SMB 1.0 access. I found it in a “how to” page from ASUS. Control Panel > Programs > Turn Windows features on or off. Expand the SMB 1.0/CIFS tree and enable all of the options, then reboot. Worked like a charm.