Why doesn't websocket work on port 80 on Mac OS?

Question

macOS

Given: chat websocket 80 port mac os
I personally have Windows and everything works. But chat users complain that they can neither read nor write in the chat. Maybe there are some nuances of using websocket on port 80 for Mac OS?? The strange thing is that, for example, everything works for them on port 5003, but those who have non-standard ports open on the network immediately fall off (because of this, I want to switch to the 80th port).