Why Flask SocketIO can not send messages broadcast nor to a specific room when deployed in a docker?

When I use my local machine and run Flask SocketIO app normally, everything works fine. Even deployed version on docker, when not used room or broadcast=True works fine. Whenever I try room or broadcast, it does not send message nowhere. Client in the web browser subscribes to a service with some string ID. When server receives request with that ID, it should notify everyone in the room about that message. I printed rooms() of clients, everything is fine, but when message comes from server, it is not sent to the subscribers even though the ID of the message i search the rooms is the same as the ID of the room.

When I deploy it on my local machine without docker, it works perfectly fine. I tested responses when I don’t use room nor broadcast and it responds okay. It does not work only when app is in the container. Can not see where the problem can be.

Source: StackOverflow