Multiplayer Network for Battle Royale

For a game with 100 concurrent users like pub g, which multiplayer network should be used.

Photon Fusion seems great, but is it unstable? if so, what is suggested?

Photon Fusion is a new solution, so, it hasn’t been as thoroughly tested in production as other Photon products, especially not for a battle royale type of game.

Battle royales are a very specific type of game; even with a complete netcode, you will need to customize it a lot to improve the QoL of your players. Things like Lag compensation and client-side prediction are what differentiates battle royales and makes them feel more dynamic for the players.

According to this article from Unity, you should use DarkRift2 or DOTS (which is rather complicated, in all honesty) to make a good netcode for a BR.

I know that the company Unordinal purchased the rights for DR2 and made it open-source. You can check them out here: https://unordinal.com/

Maybe you can try Unity Multiplay: Cloud Game Server Hosting Service (aka Multiplay) | Unity