User joining same room but won't meet/see each other

After I followed the jitsi-meet quick-installation guide on github I tried my first call and created the room “Test123”, joind with two laptops. Each Participants joined the room, but were unable to see each other. Jitsi didn’t show any other member in the room. Anybody know this issue?
Appreciate any help!

In fact, I do not know if it is a chronic problem or not, but in the infrastructure we set up about distance education, when students move from one lesson to another, sometimes they cannot meet with the teacher and although they click the same room, 3-4 students stay in one room, and another room with the teacher and several students. By logout login from the backend, they can meet in the same room. Whether this is related to the browser’s cashe problem, is it a jitsi-related problem, we have not yet identified

Did you try this:

The last suggestion made my server work perfectly.