Multiplayer capabilities

How many players does Unity support for online multiplayer in FPS.

As many players as your game server is able to handle. The only other limitation would be limitations due to how efficient is your network architecture with regards to the needs of your game.

if you use unities built in server commands, it is 32, i believe, however if you use your own custom server commands, outside of unity, and talk to that, then as much as that supports.