Thank you for your reply. “Fit to window” is NOT checked on either remote.
When I view the display settings in NoMachine for the Windows connection, I don’t see a ‘scaling’ setting. I have display quality set to medium, and resolution is set to 1920×1080 (which is the resolution used by the Windows machine).
Hmmm… So I went into “Get Info” on the Mac, and told it to make NoMachine “Open in Low Resolution”, which uses pixel doubling to hide Retina resolution from the app. That told NoMachine that my Mac had a lower resolution than the Windows machine, and it gave me a scrolling viewport onto the ‘higher resolution’ Windows machine. That’s what I’d expect. But then I cleared “Open in Low Resolution” and restarted NoMachine on the Mac, and it *still* behaves as if the Mac had lower resolution than the Windows machine.