Here’s a simple overview of the network topology.
Clients have a strict limited connection with the backend. This could be eliminated (better security) by routing all communication through the Local Server Manager. SM can validate before routing.
Essentially when a client starts the game a connection can be established between the local SM (closest via ping).
Server Manager: Manages game server instances, Game Rack, Communication with Backend (end game stats etc). Game Instances would report directly to it or through the Game Rack.