How to properly distribute traffic to servers?

Question

Computer networks

Good day!
There is an IP to which a bunch of data packets go.
These data packets are distributed to certain ports (the appropriate port is selected for each connection) The
Java program is now doing all this
. Just in case, I’ll clarify that commands can now be sent to the Java program to switch ports. Those. all packets are sent to another port.
At the moment, if this program or the server on which the program is located is laid down, then the project is completely covered with a copper basin
Question - how to make this central node more reliable?
How is this implemented in large projects?
PS The central node turns out to be very highly loaded. This is an online game. Packages sent a fucking cloud ...
PSS I'm sorry if the question seems childish. Alas, in the topic of networks, almost zero. So if it's not difficult for you - explain in a simpler way :)

Answer 1

In all the companies where I had a chance to work, this role was performed by Nginx. If filtering connections is harder than parsing urls, then write a Lua handler for your connections. Nginx+Lua is quite an indestructible bundle.