Sorry...the DMZ is the list in your Router Configuration that allows Port Forwarding (or on some Router you can actually put a device into the DMZ unprotected).
Yes the IP address of the target changed. It's 12 now instead of 9. I erased that entry because it won't let me change the target ip for some reason. Is that entry still in there even if I erased it? Is that why it keeps saying the port is already in use?
It looks like it may be stuck in there somewhere...but now we getting into Router Factory Resets which would require you to setup it up again...or Set a Reservation for the Host back to 9 and re-add it...