In recent years, 802.11ax (WiFi6) has become increasingly popular in wireless LAN environments. Compared to the older 802.11ac system, 802.11ax is said to have advantages in multi-user environments, such as the adoption of OFDMA and support for MU-MIMO for uplink and downlink traffic. On the other hand, with the increase of online classes and high-flex classes in universities and the use of online class materials and online collaboration tools, the demand to use wireless LANs for multiple terminals simultaneously in a multi-user environment such as classrooms is increasing. In this paper, we report on the development of an 802.11ax-compatible measurement system for multiple terminals using a small single-board computer, in order to investigate the advantages of 802.11ax when many terminals are connected in an actual wireless LAN environment. We also describe the results of measurements in an actual wireless LAN environment using this system, comparing 802.11ax terminals with old 802.11ac terminals, and when both systems are used together.