Exactly the issue I have been having with my Mackie DL32r mixers....
Rebooting the router, disconnecting the ipad and reconnecting, rebooting the iPad, all sometimes work. I have had to shutdown the DL32R in a show before to get it to work again.
yep, everything stops responding to the iPad. But the audio continues, except in the most severe cases... The DL32R I just replaced will lock up and the audio will work, but there is no control, no connection by ipads.
The recording stops.
The effects stop.
Reboot fixes it.