Hosting a dedicated server is a different problem from playing the game. Your GPU doesn't matter — servers are headless. What matters is RAM, your upload speed, and whether the outside world can actually reach you. This checks all three against your last benchmark.
Is your port open to the world?
We try to connect back to your public IP from our server — the same path a player would take. This only ever probes your own address, never one you type in.