[GTALUG] Problem with /dev/ttyUSB* serial port

I have a device plugged into an active USB extender that usually shows up as /dev/ttyUSB0 when I first plug it in (occasionally it will show up as /dev/ttyUSB1 when first plugging it in) . If it is /dev/ttyUSB0 when I unplug it and plug it back in it occasionally changes to /dev/ttyUSB1 . Is there a way that I can always have it show up as /dev/ttyUSB0 . I'm not sure why /dev/ttyUSB0 isn't being released and restarted after unplugging and replugging it. If I look in /dev it does disappear as /dev/ttyUSB0 from there when I unplug it but like I said it reappears as /dev/ttyUSB1? I am on Ubuntu 18.04.3 LTS . Thanks for any pointers. Jim