, sometimes the sound cuts by itself when I listen to audio on the cell phone connected to the yamaha p125, I would like to know how to solve it, the same thing happens in audio evolution

Maybe you could try connecting the two devices with a different cable..? Sometimes a bad connection can be the cause of an intermittent signal. Beyond that, your description doesn't really provide enough information for someone to guess why you might be having a problem. Perhaps a call to Yamaha tech support..?