What is the problem?
SD card working with 1 Pi 3 A+ but not with other A+ or B+
What did you already try to solve it?
Tried 3 different SD cards, moving it closer to the router, plugging ethernet into B+.
serial.log or output on terminal tab, browser error console ...)
Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ...)