https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=894769 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=894770 are duplicates
Closing the oldest one in case of minor difference I didn't spot. My first guess on "the serial connection selection is greyed out" is permission on the serial port. Advise: check it. Possible solution: please the user running arduino in the group that may read and write the serial port such as dailout.
