Too many people log in at the same time, resulting in server paralysis, or because of network, server restrictions, website upgrade and maintenance and other reasons. It will cause it not to open. If it's not a website, then you can log in again on another server.
Public online classroom platforms, such as Tencent Classroom and Netease Cloud Classroom, are characterized by large traffic, but they need to compete with others. The charging mode of their platform is divided according to interests, that is, a few percent of your online class income is used as rent.