Not familiar with opnSense, but on your PC, you can check the address it assigns - if it’s /128, it’s a single address.
My ISP does not assign a prefix for delegation unless you specifically ask for it. I had to add “request_prefix 1” to my dhclient.conf file to get a /64 I assume opnSense has a friendly setting somewhere for that. For me, the key phrase was ‘prefix delegation.’ After I got that, I could search around and get my solution.








I’ve always used heat-only, cool-only, and off modes on the thermostat, but I set them manually. Actually, I think it’s only a relatively recent firmware update that the thermostat even got dual-mode. In my climate, there’s probably not much risk of triggering both heating and cooling on the same day, anyway.
My comfort range is 68-78°F/20-26°C, though, and in I’m generally in heat mode Oct-Mar & cool mode Jun-Sep. The transition months I generally manage by manually opening windows at the appropriate time. It’d be nice to get some window servos, because sometimes it’s not cool enough to open the windows until well after I’m asleep. Or I just forget. Window program would definitely need an outdoor humidity condition - don’t want to open summer windows, even if the temp is down to 72, when the dewpoint is also 72.