Hello there Stepping Stones,
You did a great job of troubleshooting the iPad so far, and all that I can see left to do is restore the iPad. When you restore it from a backup I would test the issue. If it persists, then I would restore again but this time setup as new, and test.
iTunes: Restoring iOS software
All the very best,
More fishiness. One of the iPad minis that was working the other day was playing a song too loud. So I went into settings to turn on Sound Check. This caused it to stop playing. Same behaviour as the other mini. Would seem to connect to airplay, but no sound.
I am now suspecting one of two things. Either the wifi is too weak in that room and they are dropping enough packets to cause the streaming to stop, or its the way I have the speakers connected to the Airport Express. They are USB speakers with a separate audio jack for input. So I ahve the USB plugged into the express for power. We have similar speakers in each room. In all the other rooms, I had to use a separate USB power source because the express did not supply enough power or the speakers did not work for some other reason plugged into the express for power.
I will add a separate power source to see if that works. If not, I am running cable to the express so that it can become a wifi source.
I'll let you know what happens.