sorry for the confusion.
Here’s a summary
I installed mopidy for my Pi3 using the tutorial linked above but when I tried to connect to it I received an error (connection refused)
Searching around I’ve found that may depend when running different istances of mopidy.
So I tried to change the port from 6600 to 6601 and from 6680 to 6681 to solve it but nothing happens.
Running mopidy config I noticed that the service is still on port 6600 (also if the file is changed), so I was wondering where is the problem now.
Thank you in advance!