20 players on a P2P game sounds like a train wreck waiting to happen. True peer-to-peer (mesh networking) is only viable for games with very low amount of (1v1) players and very small data packets, because everyone needs to communicate with everyone. If using the one-player-hosts model, you have to deal with host migration and the endless amount of problems it creates (case in point: Warframe). If you can’t afford hosting dedicated servers, let the community host them for you.