what OS do you use
what arduino IDE version
are the TTN libs installed
did you select arduino leonardo
did you then select a port (different then 1)
could you upload the sketch without a problem
ok now reset uno (press button on board)
see if port changed and select that port
open serial monitor
OS: Windows 7
IDE: Arduino 1.8.8
TNN libs installed: Yes
Arduino Leonardo selected: Yes
Current port COM17
The reset button trick worked. Port didn’t change but next time I tried to upload I got a notice that I should press the reset button again “during an upload” … that did it.