Serial ports writing/reading in linux
Not enough reputation to comment:My educated guess would be that it has something to do with how Linux enumerates hardware. I think it's possible that your USB devices will have another serial-path depending on the used distro, and order of connecting them.
Are you sure that you use the same USB port every time? And that the correct USB port is mapped to /dev/tty?
You can force a HID to always have the same name by making sure you have a udev rule for it. Some info here