Apple Classroom not maintaining connection

I have a cart of 26 iPads that are used in my classroom. I have been using Apple Classroom for about a month and it has been great! However, recently something has changed and I can no longer maintain a connection with the student iPads. They appear briefly in Classroom, and then go offline, some connect again, then go offline, etc. I've tried reinstalling the app but am having no success. The school has two other similar carts that I set up the exact same and they still work perfectly. Has anyone experienced this problem?