a. Find out what board they are using 

b. Have them launch the Gcode terminal before connecting 
c. Have them launch MatterControl from the terminal 

d. Make sure they are added to the dialout group (even if they say they are have them check) and possibly send a screenshot as proof

e.make sure they clicked connect more than once 

f. get the make and model of the printer they are using


Have them send screen shots of the out puth they see in both the MatterControL gcode terminal and the in the Ubuntu terminal. They can also copy and paste the output to a text file!