Hi Markus,
This is not something we’ve encountered with iOS V14.4, so as it occurred straight after updating it might be caused by another part of the system and the new iOS, or settings that have changed.
We would recommend checking through all network settings to ensure all IP addresses are different and within the same range and/or that DHCP is working correctly and addresses are being assigned correctly.
A good old fashioned ‘turn it all off and back on again’ will often help with connection issues like this.
If you have a computer connected to the same router as your Qu, a useful test would be to see if you can connect to the Qu using the TCP/IP option in A&H MIDI Control ( https://www.allen-heath.com/midi-control/ ) as this would give some indication of whether the issue is at the Qu or iPad end.
If you’re still having issues after triple checking everything though, please contact us using https://support.allen-heath.com with full details of the setup and router information and we’ll work through it with you.
Thanks,
Keith.