I have no idea (maybe PHP). I just saw that they a short info text in the backend and display a warning when you are having a conversation with more than 4 part

I have no idea (maybe PHP). I just saw that they a short info text in the backend and display a warning when you are having a conversation with more than 4 participants. Couldn't find any documentation on what the underlying problem is. > An external signaling server should optionally be used for larger installations. Leave empty to use the internal signaling server. > Please note that calls with more than 4 participants without external signaling server, participants can experience connectivity issues and cause high load on participating devices.