Well, the complaint usually goes like this: "we recently set up service x, and it seems to be working fine. However, when we try to connect from the campus wif

Well, the complaint usually goes like this: "we recently set up service x, and it seems to be working fine. However, when we try to connect from the campus wifi, or a certain department, the service does not respond". What happens is the server gets a request from a private IP within the range assigned to docker0, and then the container replies, but because the IP is believed to be local, linux correctly tries to find something attached to the docker0 interface with that IP and fails.