Rekordbox Disconnected

Hello there , 

I used rekordbox already 1,5 years on CDJ NXS2 and DJM900 NXS2 every week at my gigs schedule.But 3 times until last Saturday night I played , trouble comes and makes me headache. 

I play around 2 hours and one of the deck is disconnected and I don't know why. I using Macbook Pro with OS.High Sierra 10.13. I restart the Mac and still playing using hard disc , and after restart back to normal again untill 1 hour next I almost finishing my play list  and the troubles come again start disconnected on Deck 1.

I don't know how to resolve this problem.I using Rekordbox ver.5.61 .