Hello everyone,
I need little help with TCP connection for one gaming server, so basically gaming server is shell and has configs to make it using remote by connecting on 3443 port but with USERNAME and PASSWORD. Is there any possible way to do it? And if it is would someone like to help me?

Have you tried using the telnet command to test connecting to that target host on that port? For example, "telenet targetIP 3443". If you see a blinking cursor, you connected. You the. Just need to figure out what client app is supported to connect to that target.