Version 0.15.1 for both instances. I'm running them on separate Raspberry Pi 3 units.
I had one unit working well and decided to purchase a second printer and its own raspberry pi 3/octoprint instance. The first unit still works well, but I cannot get the second installation to work on wi-fi (have not tried using ethernet). I changed the hostname on the second unit to "machine2" and left the original unit as "octopi" I set up the wi-fi network name and password using the txt file just like I did on the first unit that is working.
When I log into my routers, I don't see the second raspberry pi, but I do see the first as "octopi."