Dobrze this sounds like a bad connection , now if it’s a headphone socket try pushing the connector in and out quickly a number of times this can sometimes clean the contacts and work more reliably , if your contacts on your iPad are badly worn you might need to get the socket replaced, this is the worse case scenario, perhaps try a different manufacturer cable as the plug might be slightly thicker which might improve your connection and try to use gold plated plug as it will make a more reliable connection, this same issue is with lightning connector you might have a build up of crap in the connector , use a sowing pin that’s very small and carefully poke out the crap build up in the socket , if it’s in good condition change to another adaptor with good quality plug so you get a good connection , if your lightning connector is warn out it might need replacement, I hate using this connector for live gigs as it’s too unreliable for my liking.
Last work around is use Bluetooth to connect to a receiver that’s plugged in to your mixer this bypasses all physical connector problems but it’s a wireless connection which can also have its problems but a lot of people use it and are happy with it cause they were lucky enough to buy a reliable system.
Apple system sucks if you use other peoples software or devices as they assume as you plug a headphone device you want to listen to music that comes from the only player in the world APPLE MUSIC which is one of the worst players out there, they will not make it more logical to have a settings option where you choose a default audio player to select and use, this is very poor and frustrating from the users point of view but APPLE THINK THEY KNOW BEST how to remove coins from your pocke😂
Good luck