DDOS protection

It's a lot more complicated than just DDos...........
There is  "all sorts" of shit being thrown at the rust servers...

I've even seen some "underlying " protocols..... being used... (as in not  TCP/IP or UDP) but also a lot of old favorates..... "xmas/fin/smerf"
and all thru this that shit Rcon is using totally unencoded pw's over http........... what a joke.....

Nearly all of the "kids out there" (as you put it) pay monthly for commercial Rust server accounts, they don't host themselves. Of the few people who host Rust locally with a dynamic IP address (I'm one of them) the IP usually only changes infrequently, say once a month or so. It can take some time for the server to show up again on the in-game list when the IP changes, so if yours is changing twice a day you have no chance. DDNS won't help you because the server list detects your IP, not your domain.

Long story short, there is no solution to your problem with the setup you have.