Shared iPads log themselves out

We are running > 300 iPads using FileWave MDM at a middle school. We recently converted several classroom iPads to Shared iPads, and created Managed Apple IDs in School Manager. We occasionally have issues where the student logs into their Apple iD, but the iPad hangs at the password screen requiring a restart of the device, but this may have been resolved by adding an additional wireless access point (we are still watching it closely.) However, we are still seeing one annoying issue, but only in one of the classes: when the students log in with their ID, the iPads immediately log them out. They can then log back in, and all seems to be well. It only seems to happen first thing in the morning, and so far is just the one class. This is the first class to have been converted to Shared, and is also the only class using iPad 6th generation (128GB) models.

We added a second cache server at the recommendation of FileWave support but it does not appear to have helped. I'm not sure whether it happens every day but the teacher does mention it to me a lot. Is there any point to running two?

Any ideas?

Glenn