Due to the COVID-19, classes in schools have become online, hybrid, and on-demand in recent years. Various types of classes, including face-to-face classes, are now offered on campuses, and there are situations where students take online classes at school. Since students take classes using their own terminals, the university's wireless LAN infrastructure is used for communication, such as class distribution. Therefore, it is necessary to provide a stable wireless LAN infrastructure to a large number of users on campus. Operational issues for stable wireless LAN operation and measurement of the wireless LAN environment have been widely researched and developed, including detecting anomalies at the device level, bandwidth measurement at specific times, and intermittent wireless LAN environment measurement. However, today's main need for university wireless LANs is for online lectures. In this paper, we propose a new method for measuring the bandwidth of a wireless LAN in a classroom. In this paper, we describe the measurement of the quality of online lectures in a wireless LAN environment using WebRTC, which is often used for online delivery. In this paper, we describe the measurement of the wireless LAN environment specialized for the quality of online lectures. The quality of online delivery in a wireless LAN environment was evaluated and monitored.