Minecraft drops all my students out of world I'm hosting on my laptop

I have lessons planned that I've taught for several years with my entire class logging in to a world that I'm hosting, but this year it drops the entire class every 5 to 10 minutes. It lets them log right back in with the same password and doesn't log my computer out. I have over 690 GB of free space on my hard drive so that isn't the problem. I have deleted and reinstalled Minecraft Education several time in an effort to make it work. Part of the class is working on laptops, and part of the class is on iPads. It logs all of them out.