Nextcloud Talk is an extension for Nextcloud that enables chats as well as video conferencing. A decent browser and a webcam are sufficient to use that. You can also use an app for Android or iOS.
With a few simultaneous connections this usually works quite well if you pay attention to a few points, such as using a server for STUN/TURN like coturn (I will write a separate article about this).
With more than about 4 people at the same time, however, it often does not work properly because the signaling and the data transfer between the clients becomes too complex. That is why Talk warns by default if more than four people join a session (this warning can be switched off in the settings). The intended solution for larger meetings is the “High Performance Backend” from Nextcloud, which also enables several dozen simultaneous connections, but so far has not been cheap with at least EUR 4000 per year.
Now there is an alternative: the software used for the high performance backend became available as open source on Github: https://github.com/strukturag/nextcloud-spreed-signaling
However, one should be aware that this solution does not automatically enable conferences with dozens of participants – the server must also be suitable for this. The setup is also not trivial. Nevertheless, I will take a closer look at and let you know about the results.