@stephenw10 Thank you!
I struggled to reassign the LAN interface. I was told that I could not set it to a 192.168.2.1/24 subdomain. I thought I had taken notes of that episode, but I can't seem to find them. It would not surprise me if I was mistyping something (I'm not dyslexic, but I sure seem to be when it comes to correctly choosing "LAN" or "WAN").
However, after re-reading the link you provided I was able to set the LAN interface to None, which allowed installation to proceed.
Thank you for your assistance! I have a new struggle getting my legacy settings installed, but I want to wrestle with that a bit more before returning here.