Microservices solutions are more and more popular. Docker, Kubernetes are more and more popular, even the hardest opponents start to give up. Unfortunately we – Software Developers – usually do not like to focus on network protocols. That ignorance can sometimes be a blessing, but sometimes can hit us hard in the most painful time. In this article I want to focus on the Transmission Control Protocol protocol limits of source and destination ports size and why it can be painful for us.