Build Anti DDoS Solution

Hey, we are looking for a very knowlegable network security expert. we host Minecraft Servers (TCP-Gaming Traffic) and want to secure them from DDoS attacks. Right now we use a reverse proxy mitigation service that adds lags to our gameplay. That is why we want to build our own solution. We need to deal with 5-6 GBit/s of TCP traffic and if there's an attack up to obviously a lot of incoming traffic (maybe 15 Gbits). My idea is to have one powerful server that access as a reverse proxy for our applications. We need I guess a hardened kernel and a powerful firewall that stops syn flooding, ack flooding etc. UDP Traffic will be blocked out in the backbone since we don't need it. Also all other ports and typical vulnerabilites should be closed. I'm looking for someone who has experience in this field and can propose a setup and help create it. It is important that the system runs lag-free and unnoticable to players. First step would be to configure the hardware, wait for the hardware and then harden the system. Thanks for considering.