Students showing offline in classroom app

We have a BYO program. Our students have been successfully showing up on the teachers iPad in the classroom app since the beginning of the year. Since last week (mid March) some of the students are definitely online and have wifi access and Bluetooth on but they are showing as offline on the teachers iPad. This issue is increasing. These students are on the latest iOS and have no password issues. The students devices are not MDM but the teacher devices are. I’m wondering if resetting the settings on each affected iPad will help?