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, ...)
So do they even boot?
Do you get a console output on your screen?
Does it show an error?
Is the red light on your pi permanently lighted up or does it blink?
Did the green led light up at all?
What has your router to do with a working sd card?
Not much information here.
What A+ and B+ boards are you referring to? According raspberrypi.org there are several ones.
Also keep in mind, that newer boards need an update of the OS.
What OctoPi version are you using?
Also, whenever requesting help remember that we need LOGS.